Yes, the mouse writing recognition is great for free of charge.
But I am sure that some (including myself) choose the option not to select the function for your pride, "I wrote the exact Kanji, (though I know I have a bit bad hand-writing skill)", irrelevant bashing on your gadget, "this mouse is not a good one, so the site does not detect my great strokes of kanji", or etc.
It may be another good idea to be a broker to help the site owner sell the site with better friendliness with English/other languages for prospective 3/4 kyu students outside Japan.