I see your point but Punk was a bit of a unique case(except for SCSA) and usually its WWE that does the firing, not the other way around, and I am sure that getting that badge would mean quite a bit more than a title and would probably keep the superstar happy for a while atleast.Not end it, leaving Taker to retire undefeated.
Then again, that's what I want. If I was actually in that position I think I'd end up actually respecting his choice and going along with it.
as for the discussion of ending it, it's better for Lesnar to do it than some young guy, what if he does a Punk? Then 23 years really would've been wasted...