The thing about the seasonal events is that anyone can partake in them, from the lowly green-leafed level 5 to the overpowered-and-then-some level 50. The rewards have to be fitting to everyone that's taking part, not just the latter level of participants. As such, it only makes sense that the rewards be little more than glamour bait and floor dressing. I mean, really, how could the green-leafed level 5 ever enjoy a piece of equipment geared for an overpowered-and-then-some level 50? That's a really mean bit of carrot-sticking there, don't you think?