Yeah, I never had a problem with the mother dying. The problem is with Robin/Barney. They should have went out of their way to set them up as the right people for the time, but that a marriage wouldn’t work. It takes more than altering a small part of a final episode to fix this. That’s why I think the only alternative was to make it trite.
(They also could have killed off Barney, too, but killing two characters could be a problem.)
I really does feel like they planned to end the whole thing in Season 8, and didn’t think through how they extended it for Season 9.
Also, would the prime time audiences be prepared to handle a man being literally ripped to shreds by all his former conquests in glorious Technicolor? As this is the only way Barney could possibly go out.
“Kids, after that night, they were finding pieces of your Uncle Barney for the next month. The entire building had to be condemned and I got the contract to design its replacement.”
Oh, I’d think that some variant of the scene from Monty Python’s “Meaning of Life” where the condemned man is chased by the topless women would be appropriate for Barney.
Same scene basically, without the topless part (but scantily clad), and Barney running desperately away, cut to him bent over breathing heavily in the street as if he’s actually escaped, stands up, smiles smugly, straightens his tie, and BAM! Hit by a bus.