MUMPS’ bad reputation is totally unearned. Most examples online (the wiki page, the awful Case of the MUMPS article) are examples of MUMPS code from the 60s-70s when storage was a premium and enterprise-size programs had to fit in a handful of megabytes, so there was no room for readability.

MUMPS code is more readable than most languages, it’s very simple and procedural. And the ability to interact directly with durable data the same as you do local data is very nice. I don’t know why no modern languages try to do something similar.