Why can't WWE give Undertaker more world titles even after staying in WWE for 20 years+WQ?

I don't think Undertaker should have a lot of title reigns. I think he should have a long title reigns. In my opinion, it isn't the amount of world titles you have that make you a legend, it is the length of those title runs. The past two title runs have been rather short, so I wouldn't mind it if the title reign he has right now is a long one. If he has one more good, long title reign, I don't think he will be in need of anymore. Undertaker is my favorite superstar, and I don't want to see him become a title hog. He is a great superstar who doesn't need multiple title reigns to prove it.