Most definitely not. Playing online is already a little on the expensive side (gotta buy the game, the internet connection, the system you play it on; that all adds up, not to mention stuff like monthly subscriptions), and requiring online play to be done exclusively with mics is just tacking on another expense. Even if it's just five bucks for a crappy, bargain bin boom mic, a lot of people will see it as an ultimately optional thing and just not bother - and, if it becomes a requirement to play online, they may not bother with the game at all.
Of course, that's something of an extreme view. There's also the fact that some people just don't want to talk to other people when they play online (after all, a lot of online gaming is done with a keyboard). Unless you simply can't type fast enough to keep yourself alive AND express yourself, the vocal communication is entirely optional. And, in my opinion, it should stay that way. If you're feeling lonely, find a server that has a lot of people talking on their mics.