Honestly, I'm not really sure why Boba Fett became the "cool guy" of the OT, considering he only had like two lines like Adami said (though that could be a factor). Here are some reasons I've figured out that explain why people like Boba Fett based only on the OT:
-He wears mysterious, cool armor. Kind of like Vader, but green.
-He disintegrates folks
-Ruthless bounty hunter
-Weird-ass ship
-He has a freaking flamethrower on his wrist, along with a rope.
-Motherfucking jetpack
-He loves the ladies
-Makes Brian Gumble look like Malcolm X
Beyond what we're given in the OT (ignoring his silly death), all the love of Boba Fett seems to stem from the Expanded Universe. In the prequels, its like Lucas just threw the whole "every clone is Boba Fett" thing into the movie as a huge piece of fanservice.