I wish everyone reading this thread would also go read this one: collection
Where Spyder and I essentially discuss the same issues.
For the record, I love QHs and have no beef with Western Pleasure. It's a show discipline like any other, with some fabulous horses, some not so fabulouos and some training and identity issues. The criticisms leveled at WP can also apply to hunters, eventers and dressage.
WP horses move both in a slow and shortened stride, the good ones also keep cadence and rhythm. This is not the same as collection. When horsemen feel that slow, shortened stride with the exaggerated cadence, they assume that's collection. It's not. At least not in the most precise usage of the word - collection is a widely misunderstood and widely misapplied term.
I like Spyder's definition better than my wordier one;collection fundamentally changes the horse's balance, from weighted 60 - 75% on the front end to weighted evenly on all four legs. Weighted evenly, or collected, by constrast, feels like sitting behind and lighter in front.
So, to all the folks that want to insist that WP horses travel collected - okay, if that's the way the word is used inside your discipline, go ahead and call it that. Just know that it's not the same collection as the original, classical meaning or of a dressage horse above second level; and be prepared for horseman in other disciplines not to accept that terminology.
AND it is possible to like QHs, appreciate WP and still understand the terminology across disciplines, as well as the most precise definition.