Heh. Not only Inqs/DKs are allowed to play spirit. Conversely, not only (e.g.) Warlords deal with melee CPB. Juggling the attribute requirements (again, below mid-51) is an integral part of the game.
Well, first of all, yes, when you're at the stage of the game when attributes aren't a problem you can play whatever you want. I've won coliseums with melee cpb, I've won coliseums with +to next burst, I've utilized almost every strategy there is at some point except Spirit because I don't want to use something that I can just mash up with just a set of Lv38~45 charms + Dark Heirloom >_> And yes people still use Withering Touch at Lv50+ because it's just that good :V
And you know what? When I was still 50, I was POW-dump for like the entire time... I couldn't do a lot of the stuff I could do now, I never complained :V
Two points to make here :
1. There a lot of things that would make entry in an idealized spirit deck (i.e. disregarding the spirit pool altogether); from self-cleanse to armor/ward/willpower/heal to shorteners to bane extenders to anti-loldecks tools. Putting everything in a ~70c deck, without diluting it into oblivion... mission impossible. As it rightfully should be.
2. Approaches based on spirit banes can be, evidently, devastating to the unsuspecting opponent(s). No one is contending that. However, spirit banes do have a lot of counters; without any exaggeration whatsoever. Allow me to offer an example : you're 52, being able to play any sort of spirit deck you'd like. Assemble one to your liking, based on spirit banes, and then throw a few skirmishes against decks consisting of epics spam/two-three Empathic sets/Forest Medicine. See how's stuff looking from the other side of the fence. :]
Trying to play devil's advocate with arguments like these only serve to exacerbate the issue at hand, I hope you realize.
Re: 1.
What's your point?
Also, I haven't won in 1v1 with Radiant Aegis very often lately.
Misha also runs a LONG RA gear. The only reason why I've won as many coliseums as I have with my RA gear is because it's borderline shortdeck :V It gets destroyed by Spirit on a run of the mill day because of how short it is, it's only incredibly rarely I do get a win or ALMOST get a win. When you make it long, you, I dunno, ALSO DILUTE the chances of Radiant Aegis actually being drawn amidst all your -to ongoing crap? Actually, I only see long decks being only beneficial for crap like Summons and cpb... So I don't know what point you are trying to make here.
Re: 2.
Not our fault people are being smart and adapting to how potential Spirit banes can be. :V If people can see how potentially strong spirit banes can be and adapt to it, what's to say people can't do the same with Radiant Aegis? It's honestly not that bad considering, as I EVEN POSTED A REPLAY OF EARLIER, people are auto-including Storm of Alcyone and Null Barbs in most of their gears anyway :| And hey, look, remember the whole hubbub about Blood Pact? Look what happened to that - banished to PvE status. Modulation Crystals? banished to PvE status, okay maybe people still care about it in GvG. Veil of Ash? now I see only see dedicated GS teams run it instead of EVERY FUCKING TEAM EVER. Noticing a pattern here? Given the amount of shit people can choose from in order to deal with Radiant Aegis, let me enumerate:
- Storm of Alcyone which people auto-include
- Null Barbs which most people auto-include or make dedicated gears around or is easy to mash into your gear
- Aura killing charms
- Dark Heirloom + Soulcleaver/Fate of Acamar/Any spirit charm with more than 3 base Spirit damage
- Purge
I foresee Radiant Aegis needing no actual nerf. :|
Sometimes, someone wants a nerf because they just hate that charm 
man i am mad, hadn't thought of it as it done in jest