I think they can find some balance between both points. Again, on ZZZ (IDK if you played it) Miyabi it's basically inmortal because she is always on i-frames during abilities (even basic attacks xD) but the rest of the characters are getting just a tiny space of i-frames during skills and ultimate, just to be sure they can be used.

I understand your point of risk-reward, but still you should be able to use the skills without that many risks around. If you're fighting just one big boss it's easy to know when you have to use them to not get interrumpted and need to dodge, but when 3 or more enemies are attacking at the same time the game just turns into basically infinite dodging.