I'd've assumed this was like streamlining as mentioned above re swimming, i.e. there's possibly a tiny effect if you're at the level of shaving microseconds off an Olympic record time, but not really much effect if you're just pottering to and from the Co-op. Er, not that I have ever swum to (or from) the Co-op. You know what I mean. :-}

Maybe the leg-shaving is because if you wear really tight thin lycra it has the same effect as tights, i.e. hairs occasionally get caught in & pulled by the weave of the fabric, which is bizarrely painful (but nobody else I know seems to get this so maybe it's just me and my weird hairs!).