The entire world is covered in snow during winter, and look very repetitive.
AI can't possibly be programmed to understand every single aspect of every season that it's dealing with, so NPCs will undoubtedly do stupid things that wouldn't be done in that season, breaking the immersion you're attempting to gain with seasons, destroying the point of having them in the first place.
The team would have to literally retexture and redesign tons of content just for winter and summer, redirecting time that could be spent elsewhere, like designing the Main Quest, Quests in general, Items, Regions, etc. IMO, I'd rather have unique regions than seasons, but I really don't care. I also don't see why so many people want seasons, but whatever.
No. You have a good point but you're also missing a lot of facts.
1) NPCs, that can be a problem I guess. I agree with you on that. But when Bethesda has seemed to learn a lot more about AI now, and improved it way further than before; I'm sure they can tell the farmers to stop harvesting and such during the winter. It's not a miracle that is required. The AI doesn't need to change completely. Just a few simple changes like not harvesting.
2) There would be no need for retexturing. Snow is dynamic. It literally falls on the surface of every object. I'm assuming rain is dynamic as well then. Leaves could share the same dynamic feature in autumn, falling and have physics.
It's not a preset texture.I'm also not sure if you've heard of blend shading. It's a rather new feature. Check it out. It basically allows you to change the in-game texture without changing the texture. A very cool feature. Works great real-time with not many downsides it seems.
With blend shading, a script could focus to add different shades on foliage for certain seasons.
In addition, a simple but practical color grading can help even further. That's probably the easiest thing.
Thanks to these features, I believe Bethesda could pull off real seasons without too much sweat. If you think that time could be spent elsewhere, then you'll finally end up with a game being no different from any other games, or even worse concerning bringing new features than other games. If every game company would say that, we still would have had 2D graphics. But still, it's your opinion; and I respect that.
3) Environments are unique still in their shape and structure. Seasons would make them even more unique. It's like a bit of unique cream and cherry on top of an already unique ice-cream. Makes it much more delicious
I don't see why anyone wouldn't want them.