I actually like that each game can change so much between the installments, that Bioware is willing to experiment with its formula. Do they really need a more distinct brand identity than "Play a customizable fantasy hero with a band of companions (Some LI) through a story set in medieval fantasy world of Thedas"?
Because Bioware was the last AAA developer offering RTwP tactical RPG gameplay. The LAST ONE.
Now, there's some indie competition (although most is turn based), but back when Bioware unceremoniously chucked it out the door of the DA franchise back in 2011, they didn't even realize that's what they had done.
They are bafflingly unaware of their own design choices and history, which really reflects the brain drain of talent that occured in the past five years, especially in the design and gameplay departments.
I definitely prefer it to something like Assassin's Creed, churning out virtually the same gameplay and most of the same mechanics year after year with few exceptions.
For one, the gameplay for Assassin's Creed is much more simple than what an RPG series like DA tries to attain (even if the technical hurdles to create the AC series are significant). For two, your description of "a medieval fantasy game" mentions nothing about gameplay - this could be a collectible card game, a street fighting game or a Devil May Cry clone and could meet your criteria.
Street Fighter would never come out with a turn based game that wasn't a spinoff. Devil May Cry wouldn't come out with a 4X Strategy Sim unless it was some kind of bizarre promotional material. Yet Bioware changes a party-focused tactical, RTwP combat RPG into a single-character focused Action RPG as a sequel and people are supposed to swallow that, as if they are equivalent. Just like the other examples I gave would be a total joke, so is that.