Only one problem: I have zero artistic talent or ability. I've often wanted to start practicing drawing, but it was never THAT high a priority, and I never put in the effort to get a pad, pencils, start carrying them around with me, etc. An app like this can make it close to zero effort to get started and to doodle something every day.
Now there's still the problem of guidance or knowing where to start. Give me something like daily challenges or tutorials - can range from something as simple as "here's a picture of a cat, draw it" to more advanced animated tutorials - and I could see myself getting hooked. I would not mind paying for "content" or for a monthly subscription under this model.