I don't feel 4E is complex at all. Why I feel it sometimes doesn't have the 'old school feel' is that (in my opinion) it doesn't maintain the sense of wonder and adventure that a rpg should have.
I understand the reasons why many of the changes were made. I understand what WoTC was trying to do. To some extent, I also believe it did work.
However, this is something I noticed while recently GMing a session: going from level 1 to level 30 is exciting the first few times. It starts to lose its luster very quickly though. For many of my players, the wonder of an rpg comes from living vicariously through your character. While this is still possible in D&D 4E, I feel that the manner in which the current system is structure has a little bit too much of a linear push to it. Sometimes part of the fun for a player is getting lost in the life of the character; having motivations and goals; making friends and enemies; owning land; building a castle; seeing your actions have impact on the world your character lives in.
Again, I am in no way saying none of this is possible with D&D. As a game of the imagination, you are free to play the way you want to play. However, by default, I feel that the ideals upon which the game was built support a particular style. Often, this particular style assumes that certain aspects of playing a rpg are not important. It is my belief that some of these forgotten aspects carry with them the feel that people are searching for. Some of the most enjoyable quests I've played in as a player didn't require me to save the world; they only required me to live the fantasy I wanted to live through my character - regardless of whether that meant being a pauper attempting to shepherd my sheep through the countryside or a prince defending my crown against traitorous nobles or a paladin venturing into the depths of hell. I shouldn't feel as though one idea or another is considered more right or more wrong by the structure of the game; I often do.
This ability to live my fantasy is (again, in my opinion) somewhat infringed upon by the ideal that PCs should be a certain type of character and that characters should be a certain type of hero and that heroes of certain levels should be doing certain tasks. It's a little too linear. Too often, when I've been a player, I feel as though my actions don't have enough impact on the game world. As a GM, I try to give my players more choice, but I often need to bend those choices to the assumptions that the underlying system makes. I have noticed a marked difference in both my enjoyment and the enjoyment of my players when we play D&D versus a system which makes less of an assumption about our style.
Right before making this post, I had a conversation with one of my players via Facebook in which that particular player had mentioned being unable to fully enjoy D&D again after seeing what the other system we play had to offer. This caught me completely flat footed; mostly because the player in question was the one who was the most supportive of D&D and least supportive of trying something else prior to the group's experimentation into other systems. I can't always put my finger on exactly what is different, but something is indeed different about playing D&D now than it was before. I have my ideas about what I think has changed, but I imagine others have different views.
The complex part is not learning crunch and grind, it's allowing RPGs to play as RPGs. Movies, magazines, videogames, off-the-shelf modules, multiple monster manuals . . . are all about fixed narratives, which discourage open-ended play, player choice and improvisation.
It's clearly possible to play any RPG as open-ended, player (rather than rules) led and improvisational. Unfortunately, as systems become larger, get more rules to cover everything, have more options decided on the roll of a dice, favour combat-focused solutions and characters . . . play is constantly being channelled towards fixed narratives and linear challenges.
This model is seen as necessary to companies, which see themselves as the content creators instead of helping players to act as their own content creators. The ready made module or MM3 is convenient but comes at the expense of discarding the magic pixie dust made from players' imaginations.
Lego offers a pretty clear analogy. You can buy Lego kits with instructions for making a particular model for a particular setting, e.g. Prince of Persia or Atlantis. From the word go the kit, with its final outcome, follow the instructions, 'win mentality' is shaping players' experience and gameplay.
Equally, you can take a bunch of Lego bricks and make your own desert fortress or undersea kingdom. This can have all sorts of shapes and forms, be populated by your characters and 'run' your ad hoc, opened-adventures.
As a result, instead of play being channelled towards admiring a finished model and/ or playing with the model in the cast of a PoP movie, the model is ever-changing and play may touch on 1001 Nights, Beau Geste, The Four Feathers, the Mummy, your last adventure, your favourite characters - in a creative crucible filled with players' ideas and aspirations, rather than those handed down from 'above'.