Because it's hard. Also technical debt moving from Eth 1 to 2 makes it harder.
My guess is another blockchain will execute PoS better because it won't have tech debt.
My guess is another blockchain will execute PoS better because it won't have tech debt.
In mid-2018 they threw out that plan, choosing instead to implement PoS as an entirely separate chain, integrated with sharding. This entailed a delay of over a year, but it meant a minimum stake of 32 ETH instead of 1500, and an overall much more efficient and scalable system. There are three main phases, the first being the core proof-of-stake "beacon chain," which is currently running a multi-client testnet.
There have been various proposals for migrating legacy Ethereum into all this; here's the latest: https://ethresear.ch/t/alternative-proposal-for-early-eth1-e...
Tezos is another.