Actually most FPS games have some form of progression, where you get access to more powerful guns that come with more bullets and more customization options.
Strangely enough, however, I always preferred the starting weapons like the M4A1, AN-94, Krilov, XM8, SCAR etc because I found them powerful and versatile (Only exception to this would be the K-Volt in Crysis 2.) and was very successful with them.
But more to the point. We're not asking to hand out free BiS gear to everyone. All we're asking is an option to play against similary composed teams (be that solo only or premades via match making). Personally, I don't think it would hurt to try out a solo only option only for a week or two maybe.
PuGs would have a much easier time getting gear and if queue times became atrociously long for premades, you could always revert to the previous state or implement match making.
Alternatively, Recruit-restricted bracket, where new players can acquire BM gear at least without the fear of getting annihilated by BiS WH/EWH premades.
the only fair way to have a casual bracket is to make it NOT reward valor or comms at all...
poeple allways want a freakin way out...srsly yoolu can farm full BM in 2/3 days...augment it and ur jsut like an WH(not augmented)..cant you grind for 2/3 days?!