JEDIT: Plus, it makes Leia look like an even shittier mom knowing the darkness her son is struggling with and pawning him off on someone else.
Yup, that would be the characteristic “every old hero has to fail in the new trilogy” the sequels are so fond of.
It also explains 2 other things:
- The emotions on both of their faces in the flashback
- As Burbin pointed out, Leia needs a reason why she wouldn’t simply tap into the Force and become a Jedi again once Luke wasn’t coming back. This is as good a reason as any.