My guess is a few things.
First, these are symbolic, it is very hard to concretely argue that these programs are good for Americans, since even proponents of these programs say it's about "soft power". Corollary to this is that cutting something like social security is seen as cutting benefits to Americans (ditto with Defense)
Second, these programs are seen as funding "professional democrats" in a way that social security or defense are not. So this is also about cutting out their opponents support structures.
If these programs are so small, why do you care so much?
