What more proof do you need that Valve has all the data they need, yet insist on doing things their own way? The very basics of 6's - being the core classes - Valve has decided to leave it as a "pick whatever you like, how many your team needs". They acknowledged there's a 6v6 format and a 9v9 format (you can see 9v9's going to become available in MM from the game files) yet they don't understand the gamemodes.
They've know for as long as comp TF2 exists the community thinks 1 demo and 1 medic are strong enough and yet they introduce MM with no class limits. And there you are thinking they'll hear complaints about weapons.
Besides that, I'm pretty sure they acknowledged how hard it is to introduce a new weapon to the game, despite the kids outcry for more. And yet - not sure if a moment of weakness or a hiatus of new content - they release them, some of which at their very core/context are unfixable. E.g.: The reserve shooter rewarding mini-crits for the enemy simply jumping was retarded, right? Wanting to deny what a scout is supposed to do... It was later changed, but how would you overhaul it? The weapon's idea is to deny jumpers. So unless you give it a serious cons on the side, it's unfixable. Valve has a lot on their hands with no idea of what to do with it.
So there we have it: a weapon system that, instead of being a list of situational, interesting and easy to understand choices, you have a f*ckfest of pros and cons, of which most new/casual players don't fathom or bother reading, and funny enough, even some veteran players may get caught out of the loop with the changes.
Following Slin's point on "let's use them all to show what's broken and why", I'd like to see some showmatches with no whitelist to showcase the banned weapons, followed perhaps with a post-game discussion to elaborate/explicit their flaws, rather than it being allowed in leagues. Especially if mid-season changes won't be allowed.