Other problems
Part of my life is involved in finding issues with the incorporation of new technology to upgrade or 'improve' things, prior to bringing into service. There are always a bunch of knock-on issues related to through-life operations to the shiny new, some of them so significant that they result in major changes to the solution or in several cases the solution is dropped. I see both sides here, yes Rust 'can' improve certain things and if this was a green-field project, fantastic. Unfortunately there are existing personnel, skill-sets, processes, legacy code-bases etc that the shiny new has to fit into nicely.
It's very common for tech providers to go 'I've solved all of your problems!' and for the stakeholders to go... 'You do know how things work around here, right???'