Sure I get what you are saying but let's face it the whole thing was set up to put a little Thorn Birds style frisson into the love story.
In the current arrangement the Jedi just come across us utter swines.
A Jedi must not have particular attachments so to test it we will leave the chosen one's mother a slave and see what he does next?
We are supposed to care about these guys?
In ESB Yoda and Ben know just how dangerous Vader can be especially to someone with very little training like Luke (a little knowledge can be a dangerous thing but especially so when you have a guy like Vader pressing all your buttons).
They aren't saying to Luke that his friends aren't worth saving or aren't important.
They certainly don't go out of their way to make sure Luke's friends are in danger or have a crappy life to see how he will react.
They just say that it's more important he finishes the training so he can fulfill the higher goals of his friends (well at least Leia).
Ultimately they don't stop him from going either even when they have put almost all their eggs in one basket.
Sending someone to pick up Shmi, free her and have her live on a Jedi parent pension wouldn't harm their philosophy of non-specific attachment. They could have paid for her to be freed and she could then have married Cliegg of her own free will instead of him buying a bride (that's a weird set up too).
They might as well have fitted him with an electronic chastity belt if they are that concerned with enforcing their rules of attachment ("If you get any naughty thoughts it goes BOOM!").
It just paints the Jedi as a really creepy cult with a disconnect policy :
