On a point of terminology I assume you are referring to the whole board and not an individual forum.
No we are not stuck in our ways as a conscious decision was made way back in the early days as to the way that phpBB would be. Perhaps a better question would be "Should phpBB change direction as to the way it functions?" I suspect that there would be so many answers to that question covering every possible variation that it would be impossible to arrive at a consensus but the ultimate decision for that rests with phpBB's Management Team.
These are subjective. I suspect that I am representative of most members of this board when I say there some aspects of phpBB that could be improved but that most of them do not present any problems. As for "look and feel" that is customisable so not of major concern.
I don't know what the Blizzard board was like before any changes so I am unable to offer any opinion but you have to bear in mind that Blizzard is a public company with 10k employees and a $7.5 billion revenue stream - totally at the opposite end of the spectrum to phpBB.
I am not totally opposed to change where it is necessary (although that can sometimes be questionable!) but I do not agree with change for change's sake just because it seems to be a good idea.
For what you are talking about the whole of phpBB would need re-writing "from the ground up" - perhaps it is the time for that - I don't know, but what I do know is that at this moment in time phpBB does not have the resources to achieve that.
If we are not careful here we will find ourselves in a "tail wagging the dog" situation (in fact we already are to some extent!) and the one overriding factor that appears to be ignored is who is phpBB aimed at? - and that answer is the end user and in my experience the majority of end users do not want change and are basically happy with the product out there now - yes I know that some want more features but they are possible with extensions.