Because Dean had a bunch of spots and ideas planned and all of them just kept getting shot down. No one was expecting him to murder Brock and go over, just have a fun hardcore match where it looked like he had a chance. Some color too. Instead we got the biggest wet fart of a match ever, the lamest and tamest "blood feud", so Brock could gas up for a MMA fight.
I say all of that as a Brock fan.