These sorts of tools are definitely useful, especially for those that otherwise wouldn't have access to music instruction. But there would be huge pieces missing: teaching musicianship (perfect accuracy is a bad thing), finding repertoire to engage the student, arranging performance opportunities...
Basically, I think these tools replace bad piano teachers. Of course, there are a lot of bad piano teachers out there (a large percentage of all teachers, I'm sure), so I'm not saying that this sort of thing doesn't have value in increasing access.
Disclaimer: I might be a bit biased, since I have a music degree, have taken ~15 years of piano/organ lessons, and am also married to a piano teacher.
Basically, I think these tools replace bad piano teachers. Of course, there are a lot of bad piano teachers out there (a large percentage of all teachers, I'm sure), so I'm not saying that this sort of thing doesn't have value in increasing access.
Disclaimer: I might be a bit biased, since I have a music degree, have taken ~15 years of piano/organ lessons, and am also married to a piano teacher.