The point is that users without knowledge of compiling code can easily use ML for RAW recording.
Nope, that is not at all the point of nightly builds, you are completely wrong. The point of nightly builds is to aid developers by allowing users to test new features, so that developers can get feedback on those new features and fix bugs, etc. The developers only go to the trouble of making builds available to you so that you can provide feedback and testing. There is no point in automatically putting out new builds if this is not a closed loop. If there is no developer there to receive the feedback, there is no point in having the automatic public builds.
ML is not some polished consumer product ready to be used by every Tom, Dick, and Harry. It's a hobby project written by hackers (in the good sense) in their spare time. Some assembly required (pardon the pun).
I (user) think: "Why we have to compile it by ourselves just because nobody is developing?"
You realize this question reduces to "Why do we have to do something ourselves if there is nobody to do it for us?"