There's been a huge effort to get the base RHEL image size right down, so obviously getting rid of Python would help there. As for why we need to reduce the size of the base image, the answer is - as always - because containers.
(Of course, this usually gets killed pretty quickly, as dependency hell quickly brings in advanced scripting languages.)
But shouldn't interpreters be good for reducing the overall runtime code size in principle, if enough system tools run on them? High-level bytecode can be very compact.
Or better yet, compile natively, but to threaded code, and share the stdlib behind it.