I think people are getting the wrong idea that things are "getting too complex" or in the past that "things were too simple" or that "high level play is bland." I'm all but certain that at no point are we playtesting "THE CORE" (DUNDUNDUN). At any one release, I suspect we're playtesting a collage of Core + this module + that module
I wish you were right, but at the moment I just don't see how this could be true for the classes.
What you say might be true for combat rules. The last two iterations have a bunch of combat actions listed. They are not that many, so IMHO even a "softcore gaming group" (not necessarily beginners, but generally those who want a fairly rules-light game) can handle this complexity. However I also noticed that Grapple rules are already getting more complicated than I want. Do we really need to differentiate between grappling and pinning? That all depends what is your favourite level of simulation or tactics. Personally I prefer the previous simpler version, but this is an example of something that is truly a piece of cake to ignore/remove on a individual basis: if I think the two-layer grappling rules are too detailed, I can just default to grappling=pinning, and nothing else in the game needs to change. This is an example of good modularity (even if it's not specifically said in the rules that "grappling" is a module), in fact it's even more simply an example of "modularity" plain and simple.
But now let's move to classes... Take any of the classes and see how much stuff they get. To "play it well" (don't read "powergaming", just playing your class without largely ignoring some of its features), you are encouraged to understand quite an array of different mechanics and to keep in mind what you can do when it's your turn. The problem is you can't take one of those mechanics away from the game in a modular way, because you would be straight gimping that class since the mechanics rarely affect all classes equally. You can't play without skills, because the Rogue's power largely depend on them, while other classes are less affected. You can't play without combat expertise, because the fighter will be reduced to a minimum, cleric and rogue will be halved, but wizards won't be affected. If you take away one mechanic in order to simplify gameplay, you may be seriously compromising class balance, so this will prompt you to remove something else.
Finally, I think there is a huge misunderstanding on what "flexibility" really is in this game. WotC boards (therefore I guess also the feedback and the polls...) are full of positive comments on the Cleric's Channeling mechanics on the ground that it makes the Cleric more flexible. If you think about it a bit longer, you'll realize that it's the opposite: if the powers associated to channeling were just spells, you'll be MORE flexible (assuming you add the number of daily uses of the 2 mechanics together), because you would be able to choose to spend all your slots on spells, all your slots on channeling powers, or any combination; right now, having 2 silos means LESS flexible and MORE complex, because you have 2 different lists of powers to keep before your eye during the game, so when it's your turn you'll spend MORE time because you have 2 decisions to make (do I cast a spell or do I use channeling? which spell/power do I use?) instead of just 1. Not to mention the redundancy of the concept, since both things represent "channeling the powers of your gods into a magical effect".