Would it possible to add a feature to lay up some of your ships if you currently don't need them to save on expenses?
Say I've just finished a large scale war where I built a lot of war ships but I'm now entering a period of, hopefully, prolonged peace. I could then lay up some of my ships to simulate them being partially or fully decomissioned. Instead of outright destroying them, they would just become inoperable and cheaper to maintain, cutting down on my expenses while keeping a strategic reserve. During this mothballing they would not be able to move or fight but would cost less maintenance. Should I decide to activate them again they would need some time before coming online but I think this could be simulated like the old upgrade feature where, IIRC, the ship would be idle for several turns until ready.
It would help you manage your economy and bring another strategic consideration into the game, i.e. is the threat big enough to warrant activating the reserve fleet, have they become obsolete etc.
If this has been asked before, I apologise. I did a search and didn't find anything but