Do we as disc golfers see a perfect round as being all pars or all birdies?
Ball golf courses have par set so that you can always achieve a birdie if you hit your ball exactly where you want to. It's human error (or bad bounces) that cause top level pros to get par.
So in my mind, birdie golf is perfect golf. Which would mean -18 through 18 holes should be attainable.
I fail to see why making Par represent perfect golf would give us any more cred in the non-players opinion. If I see that the best golfer in the state shoots 3 up in the biggest tournament of the year I start to think that maybe these guys aren't all that skilled.
(if anything should be changed it's probably what we consider the "green" or a putt. 30' might be selling our top pros a little short.)