Being a successful game doesn't mean it had a good UI. Hell, Skyrim was a successful game and it had one of the worst UIs I've ever experienced in a AAA game.

The bars I posted aren't necessarily the ideal static UI and I wasn't posting them to show an optimal UI but as proof that people can and do memorize and use many different keys.

However, they're still better than the static UI in D:OS. If they have to go static it should be making better use of screen space.

You also suggest the buttons are too small, but the buttons to swap between the 3 bars in D:OS are tiny. Also, even excluding the smaller buttons I've got at the bottom(which could be made larger and still fit there BTW) there are more available abilities than there are in D:OS that are a reasonable size. There are 40 in that picture that are easily click-able, D:OS has 10. I would be very happy with 40.

Hell, even with the same space and slot size, if you adjusted things a bit you could manage twice as many bars:

[Linked Image]

Yeah, I'm going over the decorative junk, but it's not the most attractive looking thing anyway.

We could easily increase those bars to 15 or 20 slots in length and get 30 or 40 skills available on screen too.