It's rare because it went out of vogue like all formations do. As teams started to value possession more, tactics with an extra man in midfield became more common.
As lots of teams are now realising, and we Everton fans know all too well, possession can be overrated. What you do with it is more important.
A 4-4-2 allows faster and more direct play, with two strikers in the part of the pitch where most goals are scored from. It also aids in a 'high press' with two strikers to harrass a team trying to play out from the back. One of the strikers can easily drop back to make it a 4-4-1-1 or 4-5-1 if necessary.
I'm going to bet that more and more teams will adopt it now it's been shown that it can be effective. Until people start finding good ways to counter it of course, then another formation will become the next big thing.