Because he is now a self proclaimed Socialist, after long being under the spell of Alex Jones and the Libertarian Right.
In short, I want him here to duke it out with Lexus.
I want HSL to be a bit more livelier.
True true. That's a very interesting thing about part one. While it's not uncommon for a villain to drive the plot, it is uncommon for a villain to be both charismatic, intelligent, and "plot-driving" all at the same-time. Not only that but despite how old JoJo is as a series, I felt that Dio took villainy to an entirely different level that we haven't seen since.
Ah, k. I'm on part 7 but I got side-tracked by something. What was it? New Waves perhaps? Eh, anyway I think part 3 was probably the best one. I believe that's the one that focuses on Jotaro Kujo but it's been awhile since I read it.