I'm a lifelong swimmer. I've done it once in my life (for a national meet actually, but more as a "team activity" and less because I believe that it actually helps. If Mark Spitz could crush records left and right with that glorious mustache, a little leg hair won't hold me back)
As a cyclist I really should, but right now I don't. I always think about how much more effort it takes to apply sunscreen, and I think about how much more aerodynamic I'd be, etc... and then I think about the effort that it would take and I don't bother.
How much slower do you cycle/swim with hairy legs? Couldn't you just wear body suit?