As Rust becomes more popular while we try to bring home the last few major changes, we've had this problem a few times, where the broader community is surprised and partially shocked and disappointed at a change that has been brewing for a while.
Certainly, more effort could be put into messaging and explaining how big changes are going to effect users. Figuring out how much, and what sort of, messaging is sufficient is not easy, and somebody is always going to find something objectionable about nearly everything. Additionally, Rust is still in an alpha state, in heavy development. The project is not in production mode yet.
We're always learning from mistakes and evolving the process.
Finally, Rust is in the home stretch. In some sense, we're at a stage where we need to hurry up and just get it done, at the expense of some community fallout along the way. If Rust is good, the ill will from the churn will be forgotten in time; if Rust is bad it will die. With the attention Rust is attracting, community momentum wants Rust to stop changing, but Rust must change a bit more. Rust needs to get to a point where the design can be justified and maintained for years to come, before its own popularity forces it to slow down.