Just bad timing
Personally I think it is a little unfair to start this argument now... maybe we should all wait until the summer season when a lot of terminal development is complete. Many airports have to complete capex projects out of season so as to reduce the disruption... the only way to avoid this is to build a completely new terminal while still operating existing facilities. Obviously there are some airports that can (kind of) manage this; as we have all seen with T5, but for a lot of airports the only way to carry out works is during a slightly quieter winter season.
Granted you can probably slag off the major hubs all you like - winter/summer... it makes no difference whatsoever. But having said that, I flew from MAN T2 and thought it was brilliant. As for T1 and T3, ok, works in progress and maybe some room for improvement on the wayfinding signage... but I'm sure some of the right people will probably be reading this?!