It was a bold attempt to recontextualise the resources. I think ultimately they made bad call in making each resource individual and independent, meaning that the limit was using each power once during given time, not some shared pool of uses. It led to the need for powers not to be situational, as not being able to use the power would limit your total power pool, not just your versatility. And this led to the common complaints about tripping gelatinous cubes and scaring mindless creatures etc. But from gamist perspective it made sense why one would want powers to almost always work in such a system. Still, they dropped the ball in a major way with this, as a ton of powers required multiple targets to be effective, whilst it is a common fantasy trope having the characters to fight one tough creature.
The problem is, 4e
did offer a shared resource that could be put to use in various different things. That's how the (non-Monk) Psionic classes worked.
It was bad.
What 4e "power point" classes revealed was, when you have shared resources like that, you just spam the strongest option you have every time. Maybe, occasionally, you'll pick something else because a special situation has arisen and made that other thing best just for that situation. But most of the time, you'll just spam the best option and ignore everything else.
I'm not saying it's impossible to get, say,
one class that works this way, that has a single resource pool and manages to still be interesting and induce real choices. But making
every class work that way? No, you're going to crash straight into "spam X, it's the best choice, ignore everything else" with the possible caveat of "except in <situation, e.g. "fighting many opponents">, then use Y because it's better for that."
We already have problems with a small handful of spells being ridiculously good most of the time. Ditto, we have problems with BM maneuvers being "pick the two/three best and ignore the rest." This would just make
everyone have that problem.
Hard disagree on this. Way too gamist for my liking. Your magical power or physical stamina etc shouldn't care whether the exertion happens during a combat or out of it. Furthermore, I don't think it is even good for gameplay. Having to decide whether to use a resource now to overcome an out of combat problem or save it in case you need it in fight later is perfectly valid and interesting decision to make.
The problem is, this leads directly to poor, un-fun gameplay--demonstrably so. Because people will refuse to make the choice you describe here. They will instead take control of the rest mechanic, which the game permits them to do, and thus have their cake and eat it too.
And the only way to stop them is to either get draconian about when they're allowed to rest, or to constantly put them under verisimilitude-breaking time pressure that is somehow perfectly content with them taking multiple hour-long breaks but absolutely forbids them from taking one eight-hour break. That is, doing something like that
now and then is perfectly reasonable. Having such time pressure
all the time is patently ridiculous--but unless you DO have it all the time, then 100% of the time they aren't under such pressure,
most players will exploit it.
Players optimize the fun out of games. It's a well-known problem, and D&D has suffered from it many times.