Big problem - no. But an easily avoidable one for sure!
The core issue with using OAuth 2 for scripts is unnecessary complexity that is placed on the developers. So far, there is no sensible reason why we need to use OAuth 2.0 and can’t just use PATs. It feels like, instead of developing a solution once on the OpenStreetMap website, we will require each developer to write the same boilerplate code in each application, which seems like a waste. The idea of PATs is to handle this part on the server-side, transparently to the developer, achieving the same benefits of OAuth while centralizing the solution: easier for developers, more secure, and future-proofed.
The question is:
Why do we need to complicate script development? Is there a reason behind it? Or is it just an oversight?