To be fair Jack White's had about 50 bands on the side. All of which are excellent, imo. The guy's just got an endless pool of ideas and talent.
Meg is a far better drummer than she gets credit for (I'd argue the primary function of a drummer is to keep a beat, and provide the foundation of the song, and she does this very well indeed), but ultimately she just provides Jack White with a way to fully express himself musically. I'm sure he'll find other ways to do this, but that said, his best stuff was always with Meg. Perhaps having more (band members) is really less, sometimes.
And all of that said, they released 6 studio albums. 6 genre-shifting, evolving, hard-rocking, innovative and fecking brilliant albums. That's a lot more than most bands can boast. And for just two people, it's a monumental achievement.
*goes on White Stripes binge*