I think this is more in keeping with the anti-grognard theme of the post title rather than what the thread has become, but hey... this is the best place I've seen to make the point.
When it comes to gaming and encouraging people to game, I'm very edition neutral: I love D&D, and the enthusiasm that comes from all of the editions. I play 4E, and some people who are great gamers on this site don't like it at all, and since I respect them, I won't bash their brand of fun at all, and I think there's room in big tent for OE, BECMI, AD&D, C&C, 2E, 3X, 4E... you name it!
What's happening at the moment is that we're having a discussion about what the next edition of D&D is going to be. At a time like this, while I certainly respect other people's opinions, I'm not going to say "3D6 in order? Great! Make that the default rule!" I'm not going to say that because it's not the kind of D&D I would have any interest in playing at this point.
I think a lot of the perceived attacks on older editions are coming from the perspective that some grognards have that the old ways are best, and we should go back to them. I don't agree at all, and I'm going to participate in the playtest and forums like this to try and state my case.
When I've heard about some of the ideas being floated, and I'll pick on THAC0, I have to simply say "no!" THAC0 is in no way a good idea. It's mathematically identical to the other system, but slower and more cumbersome. Now if you want to play a THAC0 based game, great: I did so not too long ago as a matter of fact, but I certainly won't say that it should be the default for the next edition.
So I'd say that a certain degree of argument should be expected at this point (civil discourse as much as possible to help the mods out) but that arguments are going to come up, especially during the playtest.
Now after 5E comes out, I'd say that the die has been cast, and people are just going to have to live with what we end up with. Or play another game.
Right now, though, it's time to get your forces together and marshal behind the banner of my Anti-Vancian League!