Insurance companies would decide.

Raise your hand if you think that would be better.

The largest single payer in the US is the Federal government. Medicare, Medicaid, Tricare, the VA... The problem won't be fixed for the vast majority of expenditures because the government will need to perform the same function the FDA is now for it's drug costs.

Maybe. But cheaper drug development should also make for cheaper drugs, which will weaken the stranglehold the insurance companies have on drug supply and distribution.

That's what USA has now. It sucks.