I'd say that the changes in 4E were made to address issues the designers had with the previous canon, going all the way back to the beginning in some cases. Most of the changes that we're talking about here (alignment, planes) were to streamline the game and remove options that weren't used that often, were only there for purposes of being complete, or actually made the game worse (in my opinion, YMMV).
For alignment, what did we really get out of those 9 alignments? From my experience, we had arguments over what a particular member of an alignment would do (e.g., paladins and LG) and had alignments that were more trouble than they were worth (CN). I cringed every time I played in a game with a CN character, since I KNEW they'd being doing some annoying stuff in the name of "playing in character." It was as if the chaotic neutral alignment was specifically put into the game to allow people to play insane jerks. Do I miss it? Not a bit. In fact, I think the game is much better for it's loss.
Now here's the thing: I know that some folks loved that old system, and were/are greatly upset that it's gone. I respect that. On the other hand, the fact that the designers removed it made me like 4E much more as a result...I saw why they made the change and I approve.
Ditto the removal of the "great wheel" system. I know people loved it, but that wasn't me: it meant I would never buy a book on the planes for example, since it was going to have a lot of stuff in it I thought was beyond useless. The current cosmology is a lot more interesting to me, and I've purchased products as a result. It meant we got rid of the quasi elemental plane of salt and the neutral good heaven, but to me those were features and not bugs.
I could go on, and if anyone really cares I will (yep, I know that's doubtful), but the point is that there were real reasons for the changes that were made, and customers who were asking for those changes. If you don't like what's changed, I can certainly understand that: I pretty much stopped playing D&D with second edition and came back to it for third.
The point is that we have a new generation of designers trying to make D&D their own...is that part of an evil corporate vision? I don't think so at all, but I also understand why it's left some of the old guard feeling left behind. All I would say about that is there were reasons for the changes, just not ones everyone liked. The edition wars will end when people realize that the changes that get made each edition are not meant to be an affront to the old guard, they're just part of a different vision for the product.
--Steve