I'm sorry but that doesn't feel fair or interesting.. OHK never are in my opinion, especially when it isn't a supporting ingredient of a particular fight. To me, it would just be incredible annoying as I roll my eyes, reload my save point, replay a few cutscenes and begrudgingly equip the corresponding elemental materia to negate the mechanic entirely.
Interesting usage that I've seen has one-hit kills that are either non-elemental or pierce resistance anyway, because they're never used as a primary gimmick.
Let me clear up a few of the assumptions you made. 1st one.. you'll have to wait through some tedious cut scenes.
These kind of extra content difficult bosses would be specifically designed to have maybe a text dialogue or two before the fight. And you can save immediately before fighting it.
2nd, I'm not talking about the boss spamming the move... to the point where you're forced to restart. the game should give you a chance to kill it first try. essentially what im saying is this: as it stands you can get through the game pretty easily with completely ignoring resistances.
Your typical challenging game which incorporates element resistance mechanics generally forces you in most cases to have some resistance across the board, or you get messed up. Essentially between your party you should be required to have all the resistances covered by at least half. For example:
Cloud is wind/ice resistant/lightning resist... tifa is earth/holy/demi... barret is fire and etc. therefore when you get hit by the move, the character which resisted can then phoenix down and get your party going again... but if between all your characters you had NO wind and ice resistance.. that's your bad in a hardcore style game.
A game with resistance mechanics which can be largely or completely ignored, you may as well get rid of the mechanic entirely.