We really like ours and always wonder why it's not recommended more. It has great safety ratings, but on informedforlife.org, there is one category that it was not ranked in, so it makes it look lower than it really is.
It was supposed to have had some serious quality issues. A lot of it stemmed from the fact that the plant making it was new and the workers were inexperienced. Basically, teething problems. Wasn't just the Quest, but all the models that factory produced.
Once a product gets a bad rap for quality, it's gonna stick around for a while. Since it's a japanese brand, most people are just gonna move on to the competitors. If it were American, then it'd still get bought by die hard Big 3 fans despite the bad quality rep. However, since it's Japanese, many consumers are just gonna slide over to the Odyssey or Sienna which don't have the bad quality rep. Those are considered the "best" in minivans anyways so why buy anything other than the "best" if you don't have a patriotic reason? A Japanese car isn't supposed to have bad quality. That's why you buy a Japanese car (generalizing here) instead of an American one (I'm talking general perception, not necessarily reality). So, if a Japanese one has a rep for bad quality, that's sort of a kiss of death.
That's why it's not mentioned much. Had a bad rep starting out (no idea if it's true any longer) but since it didn't have any new distinguishing features, there's no reason to recommend it. Since it apparently doesn't have as many LATCH positions as the Toyota/Honda, sounds like it's lacking a bit in some things as well. Objectively, there's no reason to mention it when someone asks about which minivan they should get.
My old co-worker bought one. Around 04 or 05. Not sure exactly. Seemed nice. He and his wife liked it just fine. Might not be anything wrong. But, with the bad quality rep and no distinguishing features, it's not gonna be mentioned as a suggestion since it's just another also-ran.