To see Vitali in against another talented fighter...Wlad has the style and talent to beat Haye as he did. Vitali is a bit more rugged, and I think people are interested in seeing if he can duplicate what his brother did or more.
However I think we have to keep in mind that Vitali isn't 30 years old either. He's one-two more fights from retirement.
The other is that the two most talented + accomplished names on Vitali's record are Lennox Lewis and Chris Byrd. We all know what his record on paper shows for both of those fights regardless of how they went down.
I think it's simply a matter of interest. At HW, any punch can end the night.