Min/max would be like go 30 vit, 30 mind (for healer), or some combination of each. Obviously 30 mind gets you more heal, but the dead does not heal, and it's not sufficient to say you didn't die so you don't need the vit, because for all you know perhaps another healer was forced to keep you alive which compromised the raid in some way. A question like that has no clear answer because we don't know all the variables involved, but we debate about it because we like to think an optimal stat distribution exists.
Int/Mind distribution is not min/max. There's no conceiveable scenario a healer will suddenly bust out some nukes to turn the tide around, or a DPS bust out some heals to turn things around. If the cost of Keeper's Hymn is trivial, you'd always respec before each fight toward some combination of Mind/Vit (for heal) or Int/Vit (for DPS). You're prevented from min/maxing because it's too expensive to min/max. This isn't an issue of 'play it my way'. If Keeper's Hymn is now sold on vendor for 1 gil, I'm sure all the 'I play for fun' guys will still reallocate their stats on any fight that's remotely difficult, unless they're just super lazy or that there was no chance of losing so they don't bother.