Another feature I have NO IDEA why they changed from what worked perfectly fine in previous games...
Yeah. One of the key UI philosophies is leverage existing UI metaphors where possible, and in a game franchise, this is actually a rather easy thing to do, since you've created them all yourself earlier. You are in complete control over those metaphors.
Specifically, every time the UI director of the software reviews a UI command which deviates from what has gone on before in that software, the default answer should always be "no" unless the designer owning the petition can give a really compelling reason why it should change, and why customers will think it's better that way. That's just basic good design, drilled into programmers at an early stage of their careers. If there are deviations from what's been used before, they should be intentional to address a specific problem. Changes should be the exception and not the rule.
Frankly, the deviations in DA:I seem more whimsical (in the original sense of the word -- i.e., on a whim) rather than intentional, carefully thought out changes. I actually hope that's the case; the alternative is to think there might have been conversations during the design process of DA:I that went like this:
Bob: I want to change "pause" from SPACE to CTRL.
Alice: But we've always used SPACE for that, for well over a decade. Won't users get confused?
Bob: But in our new game, users will get the ability to jump, and we need a key for that. We're pretty sure that they'll be jumping more than pausing, because jumping is cool-looking whereas pause is strictly for those rare users that care about tactical battles, and SPACE is easier to push than CTRL.
Alice: But didn't people complain that DA2 wasn't tactical enough?
Bob: Jumping is a tactic.
And substitute "sword swinging & moving/interacting" for "jumping & pausing," and you have a similarly odd conversation.
I doubt it happened that way, of course... I suspect that it was probably a more generalized conversation around making the game more console-like, but once you've introduced a keyboard & mouse into the equation, you've already pretty much abandoned that ground to begin with, so why bother? Stick to the UI commandment that you don't move users into an unfamiliar situation unnecessarily! (It makes me want to buy the BioWare devs copies of basic UI design books...)