Minor disagreements aside I think we're on 'close to' the same page.
For me personally it really boils down to this: If you're spending enough time playing FKG that you're in a position where you're refilling stamina and churning through tons of maps to try to enhance your team, you might as well just invest in some quality daily deals or one-use gachas so you're spending all that time with a team of your choosing that you really like.
Time is money and all, so there's really no sense in investing that heavily into FKG without taking it one step further so you're actually using something close to your ideal team.
Spending a tremendous amount of time playing FKG and praying and hoping for good premium gacha 11-rolls to give you the exact team you want is a terrible idea. But if you're a more casual F2P player who just wants to enjoy some of the weekly events and have some fun with the base functionality of the game, then you might as well spend FGs on premium rolls because you shouldn't be so invested as to need the FGs for stamina or anything else. Either you're casual and gambling FGs to roll a waifu is more useful than the alternative, or you're hardcore and you'll pay to customize.
There's really no sense in being a hardcore F2P FKG player, in my opinion. The required investment of day-to-day time to get anywhere even remotely close to 100% completion of events and whatnot is really only worth it if you're obscenely invested in customizing your personal squad of favorite waifus and that's only possible with tickets.
I'm not saying you have to be the kind of whale who buys everything -- many of Nutaku's deals are complete wastes of money and there's too much fluctuation with cost. Discernment is still a virtue. But I paid something like a measly $5 for my #1 waifu Madonna, and I can't imagine investing 20% of the amount of time I've given FKG without her and a few of my other favorites.
TLDR version: If you're spending dozens upon dozens of hours playing FKG, at one point or another investing real money into the game is actually less expensive then the time you're already investing just for the chance of rolling the girl you want.