I think it's a perfect way to wrap this whole thing up for him. If you think about his return back in 2012, he's had an incredible comeback and surprisingly his more important stint in the company. Many people don't think about this but his first run with the company only lasted 2 years (if you don't count developmental), so technically, his return in 2012 turned out as less of a comeback but more as the actual start to his career in the E. He's accomplished a lot and helped the product along the way. I for one, really enjoyed most of the work he did/is still about to do with them, because after all, he's proven that he's not just a money whore but also has a feel and love for business as shown during the whole Goldberg feud, which was basically all Brock's pitch to lose in 1:26 and keep it going up until Mania.
Having him leave after finally putting over the only other guy to beat the Undertaker at Mania and therefor truly make him "the guy" in the main event of WrestleMania, is the best way to end this run in my book. I wish him the best in the UFC and hopefully he doesn't fail his first drug test right away lol