UX people tend to advocate for simple, boring stuff because they test. Like you pointed out, UX professionals like Krug, Nielsen, Norman constantly advocate for boring navigation:
"Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know."
- Jakob's Law of Internet User Experience
However, someone simply designing UI will often suggest new and complicated designs, because they don't test. If they don't test, they are not practicing UX. Even if their job title is UX designer, they are just doing UI design.
Disclaimer: Yes I am defending my UX job, which involves testing and face time with users :)