The costs are not purely economic -- you will have people struggle to read in the new script and make old texts inaccessible to young people. Additionally, this isn't a case like Chinese where Romanization has the benefit of making it easier to acquire literacy. What is the benefit of this change? I find the claim in this article that using the same script to write their language is going to bring them closer to West…
Protecting themselves from Russian insurgency, among other reasons. Kazakhstan had protected themselves before, shutting down Russian-inspired "People Republic".