Definition Updates for Defender should not use Windows Update
Defender could easily get new definitions with another mechanism than Windows Update - like every other AV tool.
It is a pain to get announcements of new updates all the time just because Defender needs new definitions.
Please do not tell me to use wsus or sccm. I have no need for either of them.
To be fair, WSUS and especially SCCM are great tools to use. You say you don't need them but have you ever tried taking advantage of them? Either way, you already mentioned the ways you can avoid Windows Update therefore Microsoft will do nothing.