My favorite part of the Public Test Realm is pre-made characters and gear vendors. Not because it's "free epics" or anything like that, not because it's particularly anything out of my reach, but because I get a fun little preview of what my characters may look like down the road.
I'm very picky when it comes to style. I adore the style of Warcraft, but other games(and even some cartoons and movies) have turned me off from them by not having an art style that grabs my attention right away. So that being said, I'll admit that even in the highest points of the Black Temple, my upgrade choices are sometimes dictated by what looks the coolest. If the ugly items are a massive upgrade for me, I'll just put them at the end of my list and hold off from looking like a freak as long as possible.
Being able to toss on full Tier 6 the last time they did pre-mades on the Public Test Realm wasn't about being super powered for a week or two for me. It was a glimpse into the future. How cool will I look a few months down the road? What if I'm going to be wearing a clown suit!? That'd be horrible! Let's log onto the PTR and find out!
Sure sure, you can always use the dressing room feature on the live servers, but nothing is quite the same as actually putting it on and running around in it. I spent a little time on the Arena Tournament PTR doing this with clones of my lower level alts, but I was disappointed to heart all of the PvE content, including mobs out in the world, have been deactivated. How am I supposed to look awesome without level 1 boars to slaughter?