To summarize your points AirBnB has these effects: 1) more supply & cheaper options for travelers/short-term renters 2) higher rent and less supply for long term renters. 3) More income for property owners (A more varied demand) 4) Less business for hotels/established incumbents.

It's a very hard tradeoff. I can't tell how to argue for one side or the other. Should we use regulation (or enforce existing ones) to help the long-term renters at the expense of travelers? Or should we let free unregulated market roll? It's not clear-cut case for me either way.