I would agree with you if Undertaker retired after 2014, but he didn't. His matches have no point to them now. Like the Shane McMahon match at 32. Even if the match was shytty, there still would have been an interesting storyline there. Shane gains control of RAW and ends the streak if he wins, while Undertaker never competes at WrestleMania again. But without the streak, why should anyone care about the match? Even in the promos, Shane said that Undertaker's legacy died when the streak ended. So he has no legacy, no reason to compete anymore, but we're still supposed to take the match seriously like it means something?
The only reason that Brock/Undertaker match is memorable is because the streak ended. If Undertaker wins, nobody would even talk about it or want to rewatch it. In the short term, it worked because Brock finally became a legitimate character again. But in the long term, it left Undertaker without a sense of purpose. You notice after 2010, he started competing only at WrestleMania for the sake of defending the streak. After it was broken, why did he come back? His matches are shyt now because he can't go anymore, which means that there's no one who can carry him. So now, he's stuck in this weird place where he should retire but can't because he doesn't feel like it's his time yet even though it clearly is.
Vince didn't think about any of this when he decided to end the streak.