The thing about adventurer is that it works well in such a narrowly defined set of kingdoms, it needs to be a kingdom with reasonably strong trashing, no good engine, a +buy (otherwise you run into the bank problem), and no strong late game attacks, those kingdom characteristics are really pretty low probability
I don't see the need for the +buy. Adventurer works great in heavily green decks with just a few big treasures. Consider a deck with 4 treasures - 2 plats & 2 golds, lets say you have 2 colonies, 3 provinces, a trasher, and 2 adventurers. Your average hand would have 1 - 2 treasures & an adventurer. This is a colony. In fact, you can green this sucker without care as most of the time you will hit at least a province.
So you end up with a hand of 18 coin and can only buy a colony ... you likely cycled past a lot of dead cards and if you pull another adventurer your next hand ... then you will most likely get a province. One of the strongest setups, I think, is forge/adventurer. Forge allows you to crunch early game cards (like baron, chancellor, steward, contraband, quarry, etc.) into plats (3 silvers make a plat, a 4 a silver & an estate make a plat, and a 5 & two estates make a plat), got rid of the coppers, and perhaps even crunch two silvers into an adventurer. 3 plats & a gold can last forever with an adventurer - cycle past the green & buy colonies most every turn from pretty early in the game.
If there are +buys on the board then it may well be better to forge into some draw engine and set up a couple of 22 coin hands.
Likewise I'm not sure what late game attack you are scared about? Cursers tend to deplete and frankly you will blow past most of the curses you get anyways. Hand size reducers are immaterial - you keep a treasure & an adventurer and play the latter - buy colony. Top deck muckers (like spy, bureaucrat, or ghost ship) are going to lose a lot of bit as you can play adventurer & tag a colony. Even something like swindler is pretty hard to use effectively, they can turn your adventurers into golds (or vice-versa) but odds are low and they run a real danger in swindling colonies -> colonies (or provinces -> provinces) and letting you get a free 4 point swing on their last turn.
I find adventurer to be particularly good when there are late game attacks (like rabble) kicking around.
Yeah, adventurer needs good trashing and has to beat out any potential engine, but it works well in games where you have plats (so it is easily worth more than the gold) and where you are going to go all green pretty quick.