The reason Vince loves Roman is two-fold. He has a good look and that matters. But also in real life and backstage he's charismatic as hell. His Talk is Jericho interview is great and he comes off cool and like a guy worth rooting for. So Vince sees a charismatic and good looking guy and rightfully thinks he's money.
The problem is that Vince's booking philosophy means they will never be able to actually capitalize on any of that.
Vince loves Roman because of his look, his back stage mentality, Roman seems to be a "yes man", and he's got a tie to The Rock.