Unfortunately, and I've been told this before by someone on the team but I don't remember who... but actually writing the logic for how the game would determine a "high value place" would be really hard. In fact, there's more trouble in defining what a "complete" region is. Maybe there's still the mapping logic that's just invisible to us, but other than that, what happens if you just enter a region that has nothing for you to do there? That makes up quite a LOT of regions. That, and any of the places that hide chests generally aren't really that hard to reach, so if it's completely random, then odds are you'll end up with a lot of perk tokens for very little effort rather than the challenge spelunking presents. It'd certainly benefit the players in terms of making them more powerful more quickly, but it would be so easy that it'd detract from the game.
Personally, maybe a little compromise would be in order instead. I think I'd prefer it if it were something like buildings in building regions could occasionally have like, a 75% chance of a boss and a randomly extended length that ends in a perk token. That'd be a bit better, because as it stands you only really go there for equipment. yeah, man, gotta get that +15 legendary t-shirt of immolation. I really like having that go-to place for equipment, but I generally stick with what I got until I suck enough to lose it so... idk, I don't end up exploring buildings as much as I maybe should.
But, if we're going that way, I might also like caves having a very low chance of not ending in a perk token, but instead being a tunnel that leads to another part of the map. You'd have to do a run through the tunnel, risking life and limb and morale, to go between the two regions until you linked them via purification, and you wouldn't be able to send survivors through. Could be nice to stumble into a cave tunnel that leads to a level up tower, or a chain of caves and level up towers that you can easily link to your main bit of land. That'd be another element of 'really nice metroidvania surprise'.