Says who and what are those reasons? I suspect the reasons are: old people got scared and stakeholders saw an opportunity.
Luckily the Internet is mostly protected from scared old people and powerful stakeholders.
Maybe in another decade when we're all older we will be willing to give up the freedoms we once enjoyed when the Internet was still young. And it will be for "mostly good reasons."
Remember the old silent movies, where the evil, mustachioed landlord was one the most popular villainous archetypes? That wasn't without reason. People looking for a roof over their heads often aren't in a good bargaining position, so often you could make them sign almost any contract. There are quite a few federal and local laws that limit what's possible in all these cases, so that your landlord e.g. can't evict you all willy-nilly. Rent control is also rather common.
Same goes for hotels, especially when it comes to security (emergency exits, maximum occupancy etc.).
Whether every single law (including this new once) make sense is another question, but my point is that this isn't something completely new, were all of a sudden the octogenarians ruling the world decided to come down on the poor cyber-startups.
I don't think this is a totally absurdly black and white case, it's no oppressive regime rearing its ugly head. Both sides have ulterior motives (AirBnB and the established hotels), but their arguments aren't totally without merit. And one thing that people keep forgetting, is that this law isn't breaking new grounds, both renting and hotels are pretty heavily regulated, mostly for a good reason. Yes, for the hard-core magical hand of the market libertarians this is another nail in the coffin, but I bet that a lot of people that get too angry in this discussion don't have problems with laws against arbitrary landlord decisions or hotel health and emergency codes.
Let's keep this reasonable…