Refinement needed? Absolutely. But, rather than changing how par is assigned (easy for major tournaments, impractical much beyond that) or the size of the target (do we really want major tournaments to have different targets than casual play?), let's refine the standards for courses used for these tournaments so that they provide the proper challenge for the top players. Sure, there may be some holes that are a par 4 for casual play that become a par 3 for the pros, but there's nothing wrong with that.
I think a lot of progress has been made on this refinement based on the tournaments I've watched online, but there's always room for further improvement.
Also, for tournaments in this top tier (however many this may be), limit the divisions to Open men & women. Build a little more of a live viewer base by not having a bunch of the local disc golf fans playing at the same time as the touring pros.