I'll start this off with the admission that I have never been a fan of the Hummer and not for environmental reasons. I have always felt it was a brand for posers, beginning with Hummer's first big champion, the Governator.
Hummer is a great example of how ideas and products on the fringe become mainstream – think tattoos, botox, and visiting Machu Picchu. Exotic, outsider, dangerous and rare, there's a cool factor to fringe products that gets lost as they become adopted by the mainstream. When every coed has a tramp stamp, how bad can that biker with the Harley tattoo really be? It's a phenomenon that Ryan Mathews & Watts Wacker detail in their book, The Deviant's Advantage.
Hummer started as a crazy idea by some high testosterone guys for whom regular SUVs weren't macho enough. Only barreling through town in a street-legalized military vehicle would properly reflect their manliness. It sold very well at a high margin until GM in their effort to expand the brand's appeal produced the H3 and soccer moms started driving them to the salon, effectively neutering the brand.
That's what killed Hummer.
The environmental concerns and $3 per gallon gasoline only hastened its demise.