@Goldkin The Zelda games aren't really known for having detailed backstories to all their bosses, I suppose. Even Ganondorf has never been much more complex than someone who wants power.
@Rosemary Kakariko is also burning when you get there, but they never explain why, or why it causes no real damage. I forget if they establish it as being caused by Ganon.
The latter games do give him more of a complex backstory, esp Skyward Sword. But in the moment in Ocarina, there really isn’t much to go on other than “he has the triforce of power and is eeeeevil, so whatever he summons must be terrible”.
I guess the case can be made that Bongo Bongo is just... chaos, and not really evil.
@Goldkin But did he wreck anything other than the well? I think I would too if I'd been trapped at the bottom of that well for so long.