A lot of the Sidi and other popular riding boots are non-leather.. Personally, I find them to be really uncomfortable and sweaty in warm weather. Regular work boots will protect you well, but don't have any armor for the shins, heels or ankles that could make a major difference in a crash.
A high quality leather boot can be waterproof and wear like iron. I never did anything to my Oxtars and they looked really rough.. A little elbow grease and viola, they're almost good as new and still waterproof!!
Leather is the best material for motorcycle boots. If you are having problems with wearing the skin of an animal on your feet, just think of all of the processed extinct beasties that you are burning and lubricating with! Maybe you should look for a pure alcohol burner with pure synth lubricants, too!
I ride with a non leather boot... its a hiking boot -- Nevados... they are available at Academy Sports... I like them because they do have some leather and some fabric... for breathabality.. and they are light and good for walking .. unlike some leather boots..