First, if they don't increase HP, the fight will be too easy. Games should primarily be fun. If players miss too often, it can be frustrating for them. It problem with turn-based games which you can't easly fix by adding extra enemies because fights will be to long.
That's the primary reason why the old infinity engine games where RTWP.
True, but unfortunately RTWP is no longer popular, so we have to live with all of this problem. I don't think there is a simple solution.
