If by scaling you mean adjustable DC that was handled by the old system. You simply used penalties and bonuses for easier or harder tasks. Yes a simple lock will be somewhat hard for a thief who isn't good at picking locks. But that is kind of the point
But check out page 36 of the dmg. Lock quality was a factor. A "wretched lock" bestows a +30% to the roll. A master lock bestows a -60.
4e's DC and check systems offer enormously more flexibility and far better scaling and guidelines than lock quality, which only appeared in 2e to boot. 4e's system will also easily with no more work let you decide things like how easily the lock might be forced, magically opened, etc all in one nice simple uniform consistent package. There is indeed no comparison here. AD&D's system is primitive and awkward by comparison.
I wasn't arguing for more diverse rogues. The 3e and 4e system takes thief skills away as the main province of the rogue and opens them up to other characters. In 2e everyone had a very low base of many of these skills that couldn't be improved, but only the rogue could really do this stuff, giving hima strong niche.
I personally have yet to see another PC try to fill the niche of a rogue, but this very flexibility allows for many positive things. For instance if a campaign wants to focus on a group of stealthy 'thieves' for instance (lets say something a bit like 'Ocean's 11') it is not only possible but relatively easy to do.
I'd also like to observe that rogue's preeminence in the realm of thievery and related classically roguish pursuits is really not in that much danger of being challenged even in 4e. Rogues have MANY utility powers (far too many to enumerate) which give them advantages in doing their thing. They automatically get Thievery and Stealth as trained skills (basically for free, even with these 2 automatic skills they still get more picks than a fighter and as many as almost all other classes, so basically those 2 are 'free'). This of course opens up all the related skill powers. There are also a LONG list of rogue-only PPs (I count something like 20) which allow for additional specialized benefits.
So, yes, 4e's approach to these abilities is a good bit more flexible than that of AD&D, but it would be incorrect to reach the conclusion that this means rogues have in any way shape or form lost their niche. If you want to excel at 'thief abilities' you'll surely be far better off building a rogue than any other class. The next best classes would probably be bard and some ranger builds, and assassins. Since bards and assassins have always been effectively rogue sub-classes this isn't really surprising. 4e rangers are admittedly sneakier than they were in AD&D, but they always did have some skill in this area in outdoor settings, so it is hardly unprecedented.
I guess if you only like combat games or want all encounters to flow like a well coordinated football play, then its a problem. For me it remains a good thing and suits my gming and pay style.
Again, i think it is important to the thief concept that they not excel at fighting. The whole striker thing turns the thief into a commando for me. Ijust don't see them in that light at all. The kind of games you end up with in 3e and 4e make the thief a lot less interesting and fun to me.
Again though, you seem to have ignored much of what I said. In 4e (and I'll assume in 3e as well) you can VERY definitely make a rogue who's focus is very heavily on the non-combat side of things. More so than the AD&D rogue, which has no flexibility in this regard whatsoever (maybe a tiny bit in 2e with NWPs, but really nothing significant). So, the 4e rogue in fact can fill 2 perfectly good character concepts, something like the Grey Mouser who has a very definite major combat aspect, and some more skill focused type who's combat capability is largely secondary. I'm a bit confused as to what exactly has been lost...
So we are back to this tactic. Even if I take the striker out of the 4e rogue i am still left with the fact that the skills are part of the general skill system available to everyone (which i don't like). So no that solution doesn't suit me fine at all. Plus there remains the problem of the 4e powers system (which i also dont like). Perhaps instead of attacking other peoples' objectivity you should take people at their word when they say they don't share your preference for 4e mechanics.
Ummmmmm.... This wasn't about some kind of subjective observation. Nor was it about what you do or don't like. I stated the factual observation that a 4e rogue can be built as either a combat specialist with some 'thief ability', or as a specialist in 'thief abilities' with some residual combat capability. This is pretty much verifiable and was something you ignored. Pointing it out is not attacking your preferences. Your likes and dislikes are really not that much of a concern to me, nor am I criticizing them.
Yes, it cuts both ways because discussions are a two way street, which is why i have never told you 4e is bad design or that your prefernces are bad.
4e's approach to this area of the game is more flexible, can reproduce (in a bit different way) practically everything that the 2e approach can, is simpler, offers tighter integration with other aspects of the system, and admits of IME many less corner cases and issues. It isn't a matter of preferences. Of course, again, what you like is purely subjective and beyond debate. I'm talking about rules and what you can do with them, not preferences. If I seemed to be making a personal attack on your preferences I'm sorry, that was never my intent. I'm just saying if you literally generate characters in 2e and 4e to implement particular character concepts I think you'd find that 4e does pretty good justice to all of them at this point, and can handle some that 2e doesn't. I think 5e can certainly tighten that up even more and make it even better, but IMHO going back to the 2e approach would not be an improvement.