I think it's more to do with 2 factors mate:
1) Hodgson and his ilk of manager are underrated
2) Viera underwhelmed a bit at Nice, and this is a harder job on paper.
To put some mitigation though, it probably felt the right time to make the "twist" call. It did feel Hodgson had gone as far as he could. As a club you seem to have a really clear idea of what you are trying to do, and I think Viera does fit that. I think of the 4 clubs who have replaced managers, and yourselves and Wolves have probably got guys who fit the brief pretty well. Ourselves and Spurs, probably less so (although Benitez is a reasonable follow on from where Ancelotti left us).
I also think, Viera may benefit from the rigidity that Hodgson had in place a bit like Martinez did here. He let's the handbrake go, but in a measured way, with the assurances that Hodgson has given them. You could get on a bit of a role.
Its tough for PL clubs, as at some point you feel you have to role that dice. I know Brighton did similar Houghton to Potter and nay only really see the benefit next summer. Fingers crossed it works out for Palace.
It's also hard, as people will turn their nose up at Viera, but English teams are probably not as appealing as people think. Like if Palace were in the Bundesliga, or Serie A or whatever, youd probably be on the cusp of European qualification. But in the PL there are just so many more wealthy clubs. Like Palace budget wise are probably not too dissimilar to say a Frankfurt, but it's just a much harder job here.
We have similar too. Like if we had our resources in any other league, I'd fancy us to push for CL, but in England we are big outsiders. It makes the league what it is really.