Only if the “upkeep” persists through death somehow, otherwise no, death would be worse in all cases.
It would suffice to know that “spamming is costly” as a general rule, without having to deal with cumbersome math equations (but you can look into it if you want). If it’s simple enough (eg. rising mana cost) players can go by feel.
Win some, lose some. You can’t always react when you need to, either. What about it?
But you want a cooldown that renders it 100% ineffective? Never mind “less”. Then have an option ala “elective mode” that restricts players from ever using an ability <100% efficiently, if that’s what it takes.
6 uses and you’re basically tapped is pretty steep, if you ask me. And if you have a huge mana pool, yes 15% can be ridiculous.
No, but the first point on your exhaustive list was ridiculous and unfair to where it looked like you were set on “Cooldowns are king” before you started reading. So I got an inclination to dismantle that frame of “See, here’s the one fatal flaw with each and every single idea”.
On matters of taste, absolutely. I’m “entitled” to say cooldowns are not functionally identical to X, Y, or Z, as a matter of fact!