It's true that when you could hit FH slice you could also hit a topspin FH. The thing is, why would someone only want to hit topspin FHs? 95% of the time they bounce right into the opponents preferred hitting zone and you do little to no damage with them. With topspin only you have to go for harder shots and push the angles more.
Slice in general is a great way to pull someone out of a rhythm. It is also a great way to not give them a ball that goes right into their preferred hitting zone. For example, a great use of FH and BH slice is to take off most of the pace and let the ball bounce twice before the service line. Against a baseliner, this is a great way to keep him from pummeling the ball and forcing him to come into the net where they are usually much less comfortable.
3X PK Ki5 315
Tour Bite Soft 17