[Neus]

Maybe, although in some of these instances (Install, Vamp Shell) I don't think it's that big of an issue, and it's not as simple of a change as you believe it is. It might also lead to confusion/perceived undesirable issues, for example; what happens when the battle ends? Do I keep the HP I gained from having my max HP increased, or does it decrease when I lose max HP? If I end a battle with 150/300 HP because I got 30 extra from Vamp Shell, I might be a little confused when after the battle my HP is 120/270. Etc.