if it's the favorite ost on board 8 now that's more to do with its cult like status and it being relatively recent. it's a great soundtrack and one of this gen's best sure, but it wasn't the best in the year, let alone of this gen. a lot of the soundtrack was simply not that good, which weighs it down a ton. yes, it has a couple fantastic pieces that are among gaming's best, but it has a lot of mediocre stuff in the middle too and an occasional bad track. it's also not very diverse at all and is very "chrono cross" in that regards. if you like the style then you'll like a couple tracks on it. if you don't, you'll hate most of it. wouldn't say the soundtrack is 'vastly overrated' but it gets more praise than it deserves, definitely.
you can point to most FF soundtracks or Xenogears for the same deal. people like to drown out the stuff that isn't that good or just plain bad in exchange for the occasional great piece and then hail the entire soundtrack as amazing. not how it works!
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The King Wang.
Listen up Urinal Cake. I already have something that tells me if I'm too drunk when I pee on it: My friends. - Colbert.