Honestly, no, I think that's wasteful. It's SOAP! I mean, if I used bar soap in my guest bathroom, and I had a party, each person wouldn't get their own goodie bag of soap anyway, they'd all use the same one.
Now...if a guest specifically asked if they could use a new bar of soap, I'd give them one. But I wouldn't just put it out to begin with.
Kimya
ETA: Ok, I just assumed the OP meant for the sink. If it were for the shower, yes, I would. I would keep mini ones on hand so that a full bar wouldn't go to waste.