Over at Grognardia, Sir Grognard had a long-standing objection to the Thief character class, primarily on the basis that it takes a single character out of play for a short time and leaves the other players twiddling their thumbs, and he slates this as the cause of the ultimate play-wrecker, the Cyberspace hacker character, which basically has its own little side-adventures in astral space every couple of sessions. Sir Grognard’s objection and his willingness to blame subsequent RPG developments like the hacker on the Thief seem to rest heavily on his critical attitude towards the inclusion of anything resembling a skill system in the rules.
Over at SOB, Chad Perrin has a brief discussion of a common point presented in favour of 4e by its defenders: that combat is quicker than 3rd edition, and “we can have more than one combat per session”. I agree with Chad that combat is not quicker in 4e, but I think part of the reason that 3rd edition games only had one combat per session is that the 3rd edition skill system was rich and detailed, and provided DMs and players alike with a wide range of opportunities to do many non-combat things. This inevitably leads to more varied adventuring and as a consequence less combat. Of course, at times the skill system gets bogged down in its own complexity (it has many idiosyncracies) but this is not the main cause of its time-eating properties. D&D 3rd edition had less combat per session because it encouraged other activities.
Now, I think I anticipate Sir Grognard arguing that this is not better, because any skill system adds a layer of abstractness to the actions one performs, and makes them less fun. I think I have read him argue, for example, that traps should be disabled by players working out a solution based on what they see, social interaction should depend on interactions between players and DM, etc. But the problem with this in practice is that it relies too much on the DM and players’ imagination. Consider, for example, the trap. In order for a trap to be a fun challenge in the Grognard vein, it requires that a) the DM be able to design it creatively and coherently, b) the DM be able to describe it in a way that the players understand, and be able to develop hints they are likely to get, and c) that the players aren’t stupid. The less said about c) the better, but I can’t build or design anything myself and any trap I designed would be completely shite, so a) is out of the window, and though I’m good at b) it can be very tricky to do in general. In these instances, abstraction enables DMs to set a rich range of non-combat challenges which the players are guaranteed to be able to interact with, and as a consequence DMs put in more challenges of this sort. The abstraction makes them slightly less endearing, I supppose, but if one is going to rest on this argument, I feel a need to point out that Grognards everywhere will cheerfully defend OD&D’s combat system, in which the hit roll doesn’t actually represent a single attack, but a full minute of dodging and feinting and taking tea with the neighbours.
Consider the full range of activities which a 3rd edition party can undertake at will: setting and removing traps, tracking things, interacting with strangers the DM hasn’t come up with a coherent plot for, spotting hidden bastards, hiding and stalking, understanding local lore, climbing walls, and more esoteric things like analysing battles to see who will win, etc. This diversity of skills means that the players can suggest actions to the DM which he didn’t expect, setting new directions to the adventure, circumventing big challenges, etc. It also means that in a pinch the DM can come up with new challenges without having to fear being uncreative on the spot, and can set multiple different adventure directions which are chosen by a roll of the dice (e.g. if the Thief can open the door they get in easily, otherwise they have to visit the sly witch, etc.) 
Skill use also gives a framework for the resolution of non-combat actions which enables DMs to pull off plot hooks and force players in a certain direction without looking like they are using DM Fiat. This is a good thing. I think all of these elements of skill use appealed to a lot of players around the time 3e was released, which is why systems like world of darkness, Ars Magic etc. were starting to take off. Rolemaster has a terribly complex combat system but its skill system kept me away from AD&D until I discovered the 3e. I think D&D has always been a bit cannibalistic, taking ideas from other places, and they did this in 3e too. In fact they did it so well that the d20 system became the monolith of the gaming world.
Of course, 4e is ripping off the computer game world, and as a consequence it is going to be skill lite. Certainly the two sessions I played only used two skills, stealth and perception (from memory) and everything else was just slaughter. I think that some people defending 4e like this, because although they enjoyed the skill-use aspects of 3e, they mostly just love killin’ shit. I certainly have had players throughout my DMing life who essentially sit out the conversations, the complex problem-solving and the political interaction, and only get interested when the blood starts flowing. For these people 4e is a better balance of combat and skill-use; but for me, based on my limited experience of 4e (and my long experience of AD&D), a slightly abstract skill system with a good engine and a good framework within which DMs can make judgements is the key to a diverse and interesting gaming experience.
 I reference no particular post in support of this claim, and my apologies if my interpretation of the justification is wrong.
 I think Sir Grognard is right about the play-wrecking properties of the hacker, but wrong to say the hacker itself is a bad character: it’s essential to the cyberspace milieu and the cyberspace milieu is a good place to play. I also don’t think the hacker’s problems can be slated home to the AD&D Thief either.
 I know that sounds really bad, but it’s true. Every DM has had an experience where the players can’t quite get into the adventure because they can’t see things his or her way, or they think something is unrealistic, or the idea he or she thought was clever on paper on Sunday doesn’t work in practice. Everyone’s imagination is limited, which is part of the reason why so many role-playing adventures consist entirely of fightin’ and lootin’. Giving people an imagination-lite way of diversfying their activities seems to me to be a good thing.
 I would add too that when they aren’t being stupid, players tend to spend a lot of time being argumentative, and the Trap is the classic example of this. Before you know it, some prat who couldn’t write an adventure if he had a module beside him is telling you that your cunningly thought-out trap would never work because of blah blah blah and couldn’t we just do blah which is what the prat in question wanted to do all along, i.e. he didn’t get your hint so he blames you.
 I would add that this happens a lot, where the cunningly laid plan a DM set is completely wrecked by creative skill use, and in my view that is a good thing.