You arent the only one, I too still have the a massive amount of the old buildings for exactly the same reason as you do, and I also know other people who did the same.I still have winter stars on most of my towns. One of my towns has several of these in the town and in its inventory, this town was at max chapter when I got them and is max chapter now. I still found them beneficial to my town. I had considered deleting them around elementals but still found them beneficial and kept them knowing how powerful they were as I hoped the upgrade option would come giving me some powerful event building options. Now I might be an exception but perhaps not, I also don't take 6 months per chapter or feel I play slowly (on my main towns anyway )
Only at the elementals did I feel the buildings were about the level to be on par with the normal buildings. and there 3-4 chapters old. but I never deleted them knowing what they could become once an upgrade option would be implemented. which I expected to be sooner but still expected to be somewhere down the line.