At OP: NO, NO, NO, NO. You have your opinion and are entitled to it. It happens to be different than the opinion I (and many other people) have.
I love DAI and have put nearly 300 hours (276 to be exact) into it already (and will probably put many times that before I'm satisfied that I've seen the majority of the content). Does it have places it could improve - yes. Is it an overall satisfying roleplaying experience with a good story - yes. Are the Bioware forums dying because of it - NO. I have no idea what you are looking at but the Solas thread alone moves 30-40 pages a day and I can't keep up. Is the overall opinion of the game bad - NO. Look at all the awards and positive fan feedback it has won. The Bioware forums tend to be the most critical of their games because those of us on the forums tend to be the fans that are most invested in the games, many of us have played all of them, read the books, the comic, own the collectors edition prima guides, art books and lore books. With all the information out there we all have a vision of what it could be, and no two visions are alike.
If you don't enjoy the game, don't play it. My husband tried Mass Effect and didn't care for it but my oldest son loves it. They both love "Shadows of Mordor" which I do not care for at all. Everyone has their own preferences and it is okay to not like something. But please don't try to speak for others, you have no idea what they like.
Things that I personally would like to see change (but I may be unique in my opinion).
1) Mix of fetch quests and deeper, multitask quests with more story behind them (some of the Elvhen shrine quests were good in this respect).
2) More pure exploration with no quest to drive you there (and fewer unreachable places within each map)
3) End boss battle did not really feel climactic enough - needed to be harder or have more story beats before you reached it. Although, as a setup for future games it was incredibly effective (Solas what are you doing?)
4) Randomized wares from each merchant (at least to a point)
5) More ability to interact with the objects in the environment (stack objects to reach things, ect.)
6) Needs to be harder (haven't played Nightmare yet so I may change my mind, but hard difficulty at least presented some challenge in previous games).
7) I would like a storage chest so I don't have to get rid of unique items (Iron Bull's sword, ect)
Things I though were great (again, personal opinion).
1) Companions - always a Bioware strength.
2) Lore - the depth of lore was fantastic. I loved the exploration of Elvhen lore particularly.
3) Crafting - I spend way to much time in the Undercroft. And the whole party should wear "hat of the Inquisitor" because it is awesome - who cares about stats?
4) Story that makes you care. Another Bioware strength
5) The quests where you had real choices did matter to the story line
6) Recognition of previous world states. The Keep is great and I love seeing how my Warden and Hawke changed things.
7) Cliffhanger - I can't wait to see what happens next, SOLAS.