I agree, and let me link-spam my take on "bringing up the rear"
in this specific case.
The question is if one can stop vertical progression in PvP while keeping it going in PvE though, since at some point, the latter will outperform the former.
Players are magpies though, and most of us intrinsically want new shinies with higher numbers to make us feel like we achieved something. Making new armour purely ceremonial like the event rewards would not do that as much, since the sense of progression would be lost, and it would only really benefit those who liked the looks of new shells.
All in all, I think that Bioware should scale the game with more variety, e.g., new warzones or a new attempt at open PvP for the competitive folks, and some storytelling parts (Kaon under Siege and the recent Theoretika quest come to mind) and tough-as-nails mechanical challenges for PvP-inclined folks. Not escalating gear would have the added benefit of keeping hard stuff hard.