I waffled about whether or not to even address this, but I figured it was worth addressing.
Every now and then, someone will come back with the "I just do it because it's fun" as a rationale for why they practice a particular move, drill, or art.
On a certain level, that's fine, because, hey training should be fun. If you hate every minute you spend in the dojo, you will probably start spending a lot less time there (and you should).
On the flip side: sometimes "it's fun" is just a way to cut off discussion or thoughtful evaluation. It becomes the last refuge of a person who has realized that whatever they are practicing isn't useful for the stated goal, so they just fall back on "well, it's fun and I like it, so there!"
Seek fun in your training, but don't use fun to justify poor training.