I can’t agree with you more. Having a combination of individuals with historical knowledge and new individuals with fresh perspectives can be so refreshing. We recently hired an external architect on the team. She’s great technically. However, I would argue her greatest contribution is fresh perspectives. She suggests ideas others (include me) hadn’t considered due to past negative experiences with team X or Y. By not being as aware of past histories or projects gone bad, she can encourage us to rethink things.
The luddite attitude is orthogonal. Does it happen? Sure. But I also have the expectation that senior staff should be identifying the New, Better Way all the time. And are well-positioned to measure “better”. It is part of providing engineering leadership. An old bird that isn’t keeping up needs a job performance message.
I don't think I can count how many times I've seen a really poorly designed solution causing real pain, and everyone even knows it's bad, but it will never change until X leaves the org, which they have no intent of doing until they're rolling out on a stretcher. Usually X has been there a long time and knows everyone - often they've created enough messes that only they understand to avoid getting laid off. Heck, if the messes are big enough, they can even look like an above average performer to people who aren't overly familiar - generally never top of the stack though, as that might get them asked to take on more work.