My guess is because people fundamentally understand that getting something for doing nothing (i.e. redistributing the new coins based on share of the collective) is communism. But let me hear the logic of others, because I want to understand this better.
Communism isn't the right way to describe it. It could be seen very capitalistic, you get paid for helping the blockchain. Bitcoin isn't different since there the miners get paid to secure the chain. The only difference is that miners have to waste resources while POS is wasteless. I rather see someone getting rewards for free than to just to waste stuff.
There is no redistribution of wealth, so the rich stay rich and the poor stay poor. Everyone has all chances so it's the way capitalism should be. It's the redistribution that kills any eco system. We now have redistribution to the rich and it will destroy capitalism in the same way than communism got killed by redistribution in the other direction.