I agree that the cool part of the Lesnar program was passing the torch to Brock as the new final boss but they didn't really play that up much.
As for Bray well....he had to feud with nothing for the Mania match which firmly established the "boring wandering confusing 20 minute Bray promo about nothing" because how do you build a feud against a fucking Titantron.? I dunno man, Bray is probably the most out there and unique character on the roster in this era of incredibly limited creative ambition - he needs big wins over big guys to feel like a real threat or a real star.
How many runs with the belt did Taker get? Taker got to destroy Dusty on his way in immediately then got the better of fucking Warrior and ended up beating HOGAN for the damn belt. They are terrified to commit to new people in any sort of big way in handing out those Ws so your replacement, full time on screen (Brock is part time and can't contribute to the show week to week) Undertaker is a fucking 500 club geek with a fancy gimmick.
To me, who started watching last year, Taker is a musty old man who murdered the credibility of his nearest modern counterpart twice (including a hilarious 2 v 4 burial of the Family on TV) took a dream match (Rollins vs Brock) away from me, got his win back from a shitty Mania match and then did the honors for a man who is untouchable in a feud that was hotshotted to Hell in a Cell. Fuck Taker.