The whole idea of stenting is to increase blood circulation in the heartmuscle, so I fully agree with that.
As far as the regurgitation is concerned, I do not immediately understand why improving blood supply would help for that.
I therefore share your concern that after stenting you still end up with a moderate/severe leaking valve.
Still, I would probably opt for the stenting, as this is done very quickly.
If the mitral leakage is not in a stage that immediate repair is necessary, you can for now avoid open heart surgery.
If, at a certain time, the regurgitation further increases and/or your heart begins to suffer from it, mitral valve repair can still be done.