Mrs. Puma- you can actually "see" more on back tumbling. Front landings are blind- your head is behind your feet so you can't see your feet land on the floor. Back tumbling you are looking at your feet, and the floor when you land.
Otherwise, what Dunno said (obviously
). It's like anything, if you practice your violin more than your piano, you'll be better at violin. Personally I also think technique has a lot to do with it- people focus a lot on BHS and getting it perfect, where for some reason FHS doesn't seem to be subjected to the same level of scrutiny- probably because of the perceived danger of going backwards vs. forwards.