I know he's not a dream appointment, and I'm pretty sure we'll get relegated under him (and most other managers), but he is at least an honest guy who works hard, and won't stand for any shirking. This is the minimum needed in the Championship. I think given our lack of work ethic, we will struggle if we go down. Trendy managers are all well and good, but managers like Cooper, Warnock, Dyche get consistent results in the lower leagues. Long term planning is out of the window, we need to stabilise the playing side of the club until our owner and board leave, and then hopefully we can start again.
Warnock's retired and when you look at his career as a whole there's a few blots on the copybook so he wasn't entirely consistent - a manager doesn't move around as much as he did based on consistency. Bielsa got Leeds promoted after many managers failed, absolutely demands a work ethic and is the absolute definition of football hipster trendy so I'm not sure what you mean in terms of ability to get results in The Championship.
Is Kompany at Burnley trendy for instance? His playing style is far removed from Dyche's but they're currently managing to sit very comfortably at the top of the Championship where, as you say, work ethic is key. Quite a few players have mentioned that he has a meticulous attention to detail which they didn't see under previous managers who were more concerned with hard work and drills.
Both credible approaches but I don't think there's a single approach that works better as a rule - it's about how good the manager is at instilling an approach.
Marco Silva got promoted from the Championship. Honest hard working guy, trendy or both? Pretty sure he'd been dismissed by quite a few as a trendy foreign sort with no actual substance but things appear to have changed. And he's certainly made a better fist of it in the Championship and now the PL with a promoted side than Steve 'Honest' Cooper has. I rate Cooper but again, I don't think there's a rule or type that works better - it's about how good they are at coaching, selection and getting their ideas across.
I've absolutely nothing against any of the names you mentioned and I can see the sense in appointing Dyche but I've no idea whatsoever what this 'trendy' term means.