Yes, the UI isn't exactly the best thing even for tablets, so we refrained from releasing it for phones. Though you could always side load it once we have it in fdroid.
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, :)