Most people are trying to find solutions to ETH problems because many people are using and therefore the idea of building a new blockchain (hard fork) needs a lot of development and resources to be a real alternative to Ethereum network, which is something that needs a good team as most altcoins are trying to be better than ETH.
As for the low fees and speed of confirmations, it is possible on Ethereum network and therefore it is not a hot topic that pushes people to invest in these currencies.
You can fork any coin, but all security and decentralization will be built from 21 validators (Binance Smart Chain, Huobi Eco Chain) to several thousand validators (Cardano). But mostly it's a few hundred validators.
https://stakers.info/For those who have not yet understood, nothing better than Ethereum has yet been invented, and any fork will be with poor security and decentralization.