That's probably true, though it's likely less about difficulty and more about certain types of games having a lot of hidden content. I don't like missing stuff. I want to know about the stuff I'm not likely to find during a normal play-through. I want all the rare items I can get.
Also, this might sound kind of strange, but I'm not really a fan of boss fights in general. I find a lot of them to be gimmicky, and if I'm ready for the story to progress, I don't mind using cheap tactics. It's not that I don't like difficulty, as one of my favorite things is to fight higher level enemies before I'm supposed to, like Deathclaws in Fallout, it's just that a lot of boss fights are kind of generic and use predictable patterns. I have a lot more fun fighting through a tough patch of elites.
i really dont care much for hidden stuff, unless they are essential to the game, like the magic and health upgrades in god of war. and also i generally preffer fast paced games, i dont like sticking around looking behind every corner, i just want to progress once im done.
honestly i love boss fights, well as long as they are good. if a boss fight sucks its not that i dont mind using cheap tactics, i actually prefer using cheap tactics. i do agree a lot of boss fights use patterns in them, its i have to do the same thing 3 times and he is done. though thats why i love god of war, even though they use these patterns they usually progress and increase in difficulty as time passes and i need to change my tactic, and in God of was ascension those patterns seem to be 99% gone. there is a boss fight in GoW A which is one of my favorite of all time, the boss fight right before meeting the oracle, patterns are completely gone, he also changes tactics so i have to change them as well. and fighting him just seemed so dynamic, it felt that as the fight went on each of us were using our strengths and trying to crush each other by taking advantage of each others weeknesses, i honestly loved it.