Lost wallet.dat are lost forever.
So keep it safe
Exactly. You can ask for total decentralized ownership, or charge-backs/ security against losses. Not both.
A fork in the Blockchain is a serious thing, and is a decision that has to have almost universal acceptance. Creating one because of a few people who lost their Bitcoin is not only downright silly, but would be unsuccessful.
This isn't a fiat currency. Increasing purchasing power is a good thing, not a problem.