Similar thing when Google shuts down a service. Yes, it was a free service, and they have no legal obligation to keep it going. But it is still rude. People have invested time into using it, and now must invest more time into finding a competing service, and transferring everything over. People are going to stop using Google's smaller services to avoid this risk.
So what obligation does Google have to keep the service alive? None. But the spirit and marketing of the site was to connect and create a community of people helping each other. And Google is going to destroy that community for (probably very reasonable) business reasons.
I guess I would like Google to give a warning that if a site doesn't reach some n DAUs then the service won't take off. It might give some people pause before putting a lot of work into something they ultimately don't have control over.
I feel users have a legitimate cause to be upset when a site is closed -- this was a real community that because Google couldn't make enough money off them, is gone.
