SBMM is the scapegoat for everything wrong with Crucible including bad connections, sweaty matches, lag switching, blink shotguns, etc. FYI, I've been playing since beta and Crucible has always been broken. The only thing that has changed is the population size, and it has noticeably gone down. Removing SBMM entirely will send the population into a death spiral.
Frustrated players quit. The below average players quit first. Then the average players find themselves below average. Then they quit. This is when the death spiral really kicks into high gear. The daily Crucible playlist start looking like a Trials run and Iron Banner will be a string of Medallions for solo players. Good luck finding quality matches when the playlist is populated by hundreds. At that point, even the above average and elite players start quitting. I remember buying Killzone Shadowfail for $5 last spring and finding only one other person in the entire world available for match. Let's not send Destiny in that direction.
I'm not saying Crucible can be fixed. It's probably too late. But SBMM is not your target. It never was.