Well, to throw my hat in the ring:
Personally (and I'd bet there's lots like me), I always have it in the back of my mind to leave C2 for another game engine. There are obviously a lot of problems inherent to C2 especially when trying to make a larger/ambitious project, which I am. The only reason I have never gotten around to switching to another engine is I've put 2 1/2 years into learning C2 and I have a decent chunk of my game finished. I hate the idea of starting that process all over, to the point that I have been in denial for a very long time about whether or not the game I want to make is actually possible in C2. It probably isn't, but most likely, we'll never find out, because the announcements + screenshots that basically show C2 in a browser was just the push I needed to move on. but not necessarily because I saw it as "bad news". It's more about what this says to us about Scirra's plans for the future. I'll be more specific:
( 
Tom or whoever's in charge here)
It seems a lot like Scirra got the money bug. It seems like getting new users became more important than keeping current users happy, to the point, that getting new users became more important than even keeping current users.
Now I'm not claiming that as fact. I'm just saying what it seems like.
And from a business standpoint, there's plenty reason to do that. I get it.
But the reason we all like C2 so much is the community. The reason C2 has done as well as it has is the community. In fact, I'd venture to say that we sell your product MUCH better than you do (most (all?) of the developers whose games are advertised on the front page have moved on to other engines!) So when you even seem to alienate that community. It's a pretty big deal.. and in the end, maybe not the best thing from a business standpoint.