lord knows why Rotterdam was preserved, I can't think of anything special about her, she's pretty small, nothing noteworthy about her design, nothing noteworthy about her service history, I guess the Dutch have some affinity towards her but meh if I can't think of anything worthy to say about her then there will be even less things to say about any cruise ship built since the 70's,
Sometimes you just get an investor who succesfully converts a ship into something profitable in the right location. IMO, that's probably what happened there. Could just as well have been any old cruise-liner. That they happened on one called Rotterdam right then and there is probably just a small bonus. It's rare that they become a long term success, but not unheard of.
Another example of a ship turned into a hotel is the Doulos Phos, built in 1914. I visited it a few times when it was a travelling book-shop in the late 90s. It opened in 2019, after having been dragged ashore in Indonesia just south of Singapore.
It honestly wouldn't surprise me if the current crisis means a number of cruise vessels will be turned into makeshift hotels for a while. More people are spending holidays in Europe, so hotel capacity is constrained. Cruise travel is at a record low, so decent ships are cheap. It won't be anything permanent, only for a few years until they degrade a bit, then they'll go for scrap.