The series was never about Hamon vs Hamon though. It was Hamon vs Vampires and then Hamon vs Stone Men. The most interesting applications of Stands all seem to be with antagonists. So, really, they easily could have just continued the series with Hamon vs Stands.
There are 6 parts with stands. It's a bit early to dismiss protagonist stands before the first one is even finished. Star Platinum is cool as fuck too.