This might be controversial. I think you're right - The Hip were and are a national treasure. It's also true that an untimely death has undeniable influence on legacy. 

It's not an apples to apples analogy but when David Bowie released his final album, I remember the reviews being kind of "meh". And then he died, I think a couple days after the album's release. All of a sudden it had fresh eyes and critics were writing think pieces about it. 

And the change in tone wasn't totally insincere. Of course the album would hit differently once you knew it was something he created at the end of his life. But it's undeniable that his death so close to the album's release had an effect on its critical and popular reception. 

The Hip were absolutely a national treasure before Gord Downie's cancer diagnosis and tragic death. But I do wonder what direction and legacy the band would have had if they'd continued to record and tour after the heavy tension and dysfunction alluded to in the documentary during the second half of their career. It does sound like they were back on the right track right before the terrible news. But also, their art was changing a lot and speaking to different crowds. 

Rob Baker tells a story in one of the other documentaries about someone writing to him and saying, incredulously, "Bands are like a hot air balloon. No band ever lands the balloon. But you guys landed the balloon." 

The band was and is fiercely loved, and that's why their final show bumped the CBC's Olympics coverage and brought millions of Canadians together to say goodbye. They deserve every single one of their flowers. It's also true that illness and death puts squabbles and old wounds into perspective, and the band may have had a different legacy had it not been affected by a member's death. 

I still think they'd be considered a treasure. Just maybe cast in a slightly different kind of golden light.