Number of people gained on releasing a linux port is low, since most of them are existing customers. Thus the cost to port to a new platform is not justified.

Why not contribute a little every month to Krita so that it can hire more developers to work, if Krita has the budget of Photoshop, it would just blow it out of water.

PS: Right now there are 5 full time devs and 2 part time, :)