Why do the BHC think that the person who apply for...

Why do the BHC think that the person who apply for a visit visa to UK will never leave the UK ?? No doubt UK is a beautiful country but there are so many like me and my wife who love their motherland beside all the difficulties and poverty.
BHC simply refused visa for my wife saying "....... BECAUSE I AM NOT SATISFIED THAT YOU INTEND TO LEAVE THE UK "
We just wanted there should be someone with her from the family during the time our daughter delivering her first child.
I think BHC should think over on such request.