Five custom classes is simply insufficient for this game. MW has a pretty varied multiplayer experience from smaller TDM to objective modes to huge ground war games. COD4 and MW2 offered far less variety in their multiplayer yet even back then there was an avenue for earning additional slots. I'm constantly having to change my classes around in between matches to account for the large pool of weapons I want to play with, why put a hard cap at five custom classes? Really it's a testament to the variety of gear on offer that more than five is a necessity, so stop being so stingy!
You and everyone else that has commented on this are right. Its in mainline back at the studio and weve been tinkering with it. Im not sure which update its in but I think its next. Believe it or not it can cause horrible bugs if not tested properly. Im not certain about all this so don't get fired up on me if Im wrong. Since I've commented here Ill stick with the issue at the studio.
"Just a reminder, time does not allow me to scan the entire sub and acknowledge everything problem, comment, or feedback day to day but I try and help whenever I can."