This is definitely where I want to go eventually. Giving the user the option to control what objects to store into Flash. We don't want to waste any space for people with things they aren't actively using, especially random community objects. SuperCollider has an approach kind of like this actually where adding your preferred extension objects takes a build cycle and but then they're available to your patches until you decide to uninstall them.
On the other hand we do have an entire extra megabyte of flash available to us (we have 2MB over Core's 1). My intuition is that this is huge compared to the amount of data we need to store for objects if we're reasonably clever about not being wasteful when we store them.
Some objects need to be parameterized and stored more compactly. Take the basic example of mixer objects. Instead of having Mix1, Mix2, ..., Mix8 all stored separately, we want some kind of MixN that takes the number of inputs as a parameter and generates the appropriate object. This might be a behind the scenes optimization. At the patcher level, it could still be exact sizes like we're used to like Mix2, etc.