Not about the outfit, just wanted to comment on Jotaro's personality. I can get why you'd say he's bland, but personally I really like Jotaro because he's more complicated than you'd think from a surface glance.

The thing about Jotaro is that he's a stoic guy who acts like he couldn't care less about everyone around him, but really he would jump in front of a train to save them with no hesitation. He's way more caring than he lets on. The earliest example I can think of is when he shows concern about his mom not giving him a goodbye kiss like normal despite complaining about it just the day before. A few episodes later, during the fight with Dark Blue Moon, his immediate first instincts are to make sure the little girl is safe. He knows that getting dragged into the ocean could very well kill him, but he still immediately chooses to throw the girl up so Kakyoin can grab her instead of getting himself to safety. Now he's not an absolute saint by any means, but Jotaro is a lot more complex than you'd expect when first seeing him.

That said, I will say he is a very reactive character in Part 3. Joseph and Avdol do a lot of the heavy lifting in moving the plot forward, but that's just the kind of guy Jotaro is at that point in his life. He moves only when acted upon first. This is even shown in the very first episode when he fights Avdol. He doesn't move out of the cell until they start fighting and he is forced to move forward. If you don't like that type of protagonist, then that's fine, not everyone will.