Ninety-degree angles do not exist in nature. So you're going to get two schools of thought: UI should look more natural (and therefore round off any hard edges), or UI should intentionally embrace hard edges, as a declaration of defiance against entropy, just like any other human endeavor for industry, progress, stability, and reliability.

We used to build systems that we wished would stand the test of time. Now we build systems that only last as long as PMs care about them and their warranty period runs out. What do our design choices say about us?