Given that they keep postponing the transition to PoS, wouldn't it be smarter to remove the artificial difficulty increase and make the network more efficient?
Fwiw the transition doesn't look that far off now. There's a working multi-client testnet for the new (separate) proof-of-stake chain, and a recent proposal by Vitalik to transition the old chain into it more quickly than previously expected: https://ethresear.ch/t/alternative-proposal-for-early-eth1-e...
The reasoning is that somewhere down the line introducing an ice age may lead to a contentious hard fork. Better to include it upfront so that expectations are set that PoW on Ethereum is not a long term thing.