Yeah, why not? mBTC can be easier for micro transaction and small earnings for us newbies, whereas BTC are more used by miners and large companies. I suppose different units of bitcoin can be used in different places, so each is useful in some way. Many sites now also offer mBTC as a unit, like coinad, but it makes the earnings look small.
Yeah, I agree with you. Btcclicks use it too. So, the member can feel if they are gain a great value..