Why are stem cell therapies more preferred (theoretically) over current measures?
Stem cell therapy was never going to replace surgery, and it isn't supposed to. We just don't have the tools to move stuff around inside the patient without breaking the skin. 

Stem cells therapies offer replacement parts for organs that can't regenerate themselves. For example, after a heart attack the heart often forms a scar where heart tissue has been injured or died. The scar often doesn't conduct electrical signals properly or doesn't beat at all, both of which are a problem for a heart. The scar can't be surgically removed, because there's nothing to replace it with. Stem cell therapy would provide new heart muscle to replace the damaged tissue.

There are of course exceptions, some stem cell therapies are injected and left to 'settle' in the right tissues. That kind of therapy generally doesn't replace a surgery either, because that kind of problem can't be fixed with surgery at all.