When you want to ship features that essentially will have to be maintained forever, and can't be meaningfully changed after shipping, you don't rush into things without a strong belief that you've gotten things as right as you can.
Consider the bit in OP about wanting to add a Move trait and deprecate Pin, and reverse the semantics so types are immovable by default. That's a difficult change to make now, after async has been stabilized. Obviously in this case the longer, deliberate process didn't save them from this (apparent) mistake, but overall new big language features should never be rushed.
> For example, this "four year plan" should be implemented in 6 months at most, not 4 years.
Consider the bit in OP about wanting to add a Move trait and deprecate Pin, and reverse the semantics so types are immovable by default. That's a difficult change to make now, after async has been stabilized. Obviously in this case the longer, deliberate process didn't save them from this (apparent) mistake, but overall new big language features should never be rushed.
> For example, this "four year plan" should be implemented in 6 months at most, not 4 years.
Now that just sounds reckless to me.