The game play, story, and character development of DA2 were great. The reused environments were a result of a stunted 15 month development cycle that was forced upon Bioware by EA wanting to push the game out of the door way before it was ready. This was confirmed by a few people at Bioware, one of them being David Gaider. In comparison, DA Origins had a 5 year dev cycle, and by the time DAI comes out, it will have had a nearly 4 year dev cycle. Inquisition is going to be total quality, and I can't wait. DA2 is still a great game full of great moments though, and it doesn't deserve nearly all the hate thrown its way. It quite like ME3 in that sense.
15-month cycle was quite short, but it's not like it's a record low. Some other development notes suggest that the game may not have been a full fledged sequel from the first place but an in-between stuff, when it was called Dragon Age Exodus (which I consider a better title). Moreover I think Bioware could have said no to the development cycle, seeing just how much right they had (and still has) on their projects. So my guess is that after 5 years of working on DAO devs wanted to do things fast this time - which, unfortunately, resulted in another 4 years of development for the third game, nearly a reboot in terms of the game's system.
But IMO going forward Dragon Age needed this, and it should have happened with DA2 already. I liked both games at the end of the day, it might even be the only one from the fantasy genre I can actually enjoy, but it's not what fans were promised waaaaay before DAO was first announced. There were lots of ideas back in DAO that ended up being scrapped and backtracked, especially all the ambitious attempts to make it more action-oriented, and in the end what we got was an old but quite unbalanced game that could easily show its seams. Making it truly action-oriented and tactical at the same time required something more than DA2, and from what I've seen so far they have found the right place. Hopefully, all of this will pay up in October.