Every project has a different goal and industry, you can not expect all of them to make it as a global payment system. Let's say a pharmaceutical token based project, the project is limited only to buy the medicine and in this area. Does that mean, this token is bad? no, because this is what they are aiming for.
Proof of Stake is a consensus, the use case depends on the project itself. Why people love it?
It is because it is cost effective compared to POW in running the blockchain, you can get a passive income from holding it, the majority POS project are faster in term of transaction speed compared to POW.
It's correct! And of course, as mentioned above, Proof of Stake is only adequate for altcoins used for payments and regular transactions by a large community. PoS isn't wrong but there're many projects used it as a slogan to call for investing.
Ethereum will succeed even when it switches to the Proof of Stake algorithm. I firmly believe in that!