I used to think converting from handwriting to LaTeX would be a really useful program and save a lot of time, but after typing LaTeX on a regular basis, the input speed is really not an issue. Sometimes I'll encounter a symbol I don't know, and then I draw it in here [1] and remember it for next time. When doing math, it's definitely not the bottleneck in getting my work done. I would definitely be slower with handwriting conversion, especially when you factor in fixing errors in its translation. I only see handwriting conversion being useful as training wheels for beginners, but would be interested if someone has a different experience.
Automatic recognition from PDFs is more promising for accessibility and reformatting, and also seems to be easier to do since typeset math is easier to recognize than handwriting.