Speaking as a product leader who has been in a position to decide on these, I'm not opposed to major UI overhauls, but many that have been proposed to me:
- Are motivated by a design team that wants to justify their jobs or make a mark on a product, with the UI considerations secondary.
- Have major issues and design weaknesses themselves.
- Throw out important aspects of functionality in an attempt to be "fresh and simple".
- Ignore that we had our last major overhaul 12 months ago, and that one was in response to the major ovehaul 24 months ago.
Requiring evolution rather than revolution is a hedge against these problems. I'm not generally opposed to overhauls because I'm familiar with the importance of UI. For example, I'm very unhappy with Robinhood as a trading platform, but damn, switching to Fidelity is painful because their UI is so terrible.
I wish I more consistently got to work with talented designers. I put a lot of effort into getting good designers, as poor designers can wreak havoc.