Because he has just taken care of the number 2 of the division, and recently had his first baby. He probably wants an easy fight next. Tyson Fury is not an easy fight, believe it or not, and it can grow in popularity in the mean while.
HBO will also need time to build up a Fury fight. Jennings, though he's not more accomplished, is still a rated contender and, just as importantly, is American with an unbeaten record. Considering HBO just made a multi-fight commitment with Wlad, it makes sense that they'd want a U.S. based fighter now. The dream scenario for HBO is Jennings, Fury, and Wilder. Though, if Stiverne knocks out Wilder emphatically, they'll not complain too much.
Jennings is a solid title defense opponent. Props to Wlad. After he beats Jennings, I hope he can unify against Wilder/Stiverne winner. That should be his priority. Tyson Fury should not have priority. Wilder, Stiverne and Jennings all rank above him.
Wlad's deal with HBO involves 03 fights. Pulev was the 1st one and Jennings is the 2nd. I agree, they wanted to stage a Wlad fight at New York against an american fighter (Jennings or Briggs, thankfully Jennings agreed). The 3rd fight of the deal will probably be unification against Wilder or Stiverne. I don't see Fury getting involved, at least not in 2015. Maybe as an alternative if the Wlad-Stiverne/Wilder fight becomes complicated.
Terrible fight. Jennings is not ready for Klitschko. He got a gift in the Mike Perez fight. I would have preferred Briggs vs Wlad.