I don't think its really fair to pigeon hole, but I think the Klein ownership was about both the Material and the paint.
In the first instance there was the WOW factor, the massively Oversized "coke can" sized aluminium combined with the Fork even seeming to dwarf the cannondale offerings at the time. then factor in the fluro White green and pink paint that was so seen at our race events, it kinda made a statement right there. Further factor in the Price ticket, and those with deep pockets dug deep, regardless of whether or not they could exploit its benefits.
Hitting the weight barrier here in the press at 20lbs ish, when other top end bikes were struggling to hit 25lbs, it was a marketing departments wet dream imho.
From this point on it was simple.....it was about weight through material and you got sublime paint to boot.
Klein was associated with this from the outset, sadly every company across the world jumped on board with the material/weight etc, and every where you turned Aluminium was everywhere, it just got cheaper and cheaper and cheaper.
I wont comment on Mountain goat, as it was a Niche here really IMHO.
Bontrager was slighty different in that they were available, they didn't rely on any advertising, or Trick paint or galloping scientific leaps in Aerospace technology to sell it, it was always considerably more underground (and constantly sold out I must add too).
It was skinny it was svelte it was Bombproof, and in keiths own words it was "Fundamentally Cheap".
Like I say unfair to pigeon hole really, but come the end of the Trek Era for both marques, there were certainly a totally different customer base for both brands.
They were complete opposites.
Very well said. Damn, I have to get me a (vintage) Bontrager now!!