Both of those games have several methods of mitigating or ignoring misses, so it's hard to gauge how much of an annoyance it could be without most of the skills and passives in the game. If you plan on having effects like this it should be OK to keep missing in rt combat in (and let the player abuse them for evasion builds). I just know that people meme on Morrowind to this very day for its roll based hits in a rt game.