Side overhangs are very often less than front overhangs.

How do you plan on handling the molding that sticks out further than the sides of the vanity? If the molding hits the side wall, then you will have a very skinny piece of floor between the wall and the vanity foot which will be difficult to clean. And if the lower vanity molding hits the baseboard, there will be a larger space between the side of the vanity and the wall.

My countertop was made flush with the wall on the right side, with an inch or more overhang on the other, open, side. It didn't look weird at all. There is really no other way to do it.

I'm going to talk with my cabinet builder and ask him about the molding, as I understood that the vanity would be built and installed flush with the wall. Perhaps the molding on the sides will be eliminated to enable it to be installed flush. I really don't want a space beside the vanity and the wall...just a tight space to have to clean. Thanks for both of your replies.