Because they exist elsewhere and I think it would be cool to see some 3x3s that are limited to mobile games.Hard mode: Only mobile exclusives, though with how cross platform everything is these days that's a tall order.
I'd say there are two types of mobile exclusives: tiny passion projects nobody's heard about, and ad-ridden skinner boxes with enormous numbers of downloads. Everyone else understands that multiplat is the way to go if you want to get paid.