I loved Valkyrie Profile so much that I went through the trouble of writing a review for it 15 years ago (I have long since forgotten that account's password). Slight cringe of re-reading my old writings aside, for the most part, my opinion is still the same. The things I would disagree with old me are:
1) "a tad disappointing in the plot department" - I think this is a misstatement. The plot is not a tad disappointing. It's more, the way the plot is delivered that could be considered disappointing (e.g. requires a walkthrough).
2) Any references to "translation" being good or not - Without understanding and reading the original Japanese script, I or old me would not be in any position to judge whether the translation is good or not.
3) "I could care less about..." - Incorrect grammar. That should be "I couldn't care less". If "I could care less" about something, then that means I still have the bare minimum of care of said thing.
4) "To me FMVs are a waste of CD/DVD space." - Not true. Even if a game has no FMVs, it's not like that space would be filled by anything else anyway so you might as well inflate it with high quality eye-candy movies.
Anyway, it is true that VP's music is a bit rough to listen to - I certainly wouldn't it play it at 100% volume unless you want to irritate your ears. Also for an RPG, VP is unique in that once you get access to the world map after the very long introduction scenes (close to an hour), you can basically skip the whole game so you can easily listen to most of the music in context (e.g. the towns and dungeons that are unlocked in each new chapter).
As for VP2's music, I haven't heard Motoi Sakuraba's entire (massive) discography, but so far, VP2 is for me his magnum opus. As you mentioned, VP2's normal battle theme is really something both in terms of personal listening enjoyment and in context (Norse gods battlin'). And as you also mentioned, VP2 does indeed have a generally lower profile (pun unintended) subdued sound (no problems raising the speakers to 100% here). VP2 also has the honour of having one of, if not the most fun and addictive RPG battle systems (the battle theme helps too).
Here are my 5/5 tracks:
A Motion of Finishing Blow (perfect battle theme)
Sank Memories, More Deep
Raid The Mighty Force (good example of a subdued track, considering it's played in a Volcano context)
Disturb The Doubtful Sleep (plays in the only dungeon that is also in the prequel)
Junk Modulation (more subdueness, this time in a battle context)
Dancing Without Malice or Mercy
My ratings logic:
0/5 - Little to no musical value, technically or subjectively.
1/5 - I understand the artist's intentions with this song but it's not for me.
2/5 - Might give it a chance every once in a while or it's a bit of an acquired taste.
3/5 - Fairly average, it's not overly amazing, but not bad either, mainly just background music or non-active listening.
4/5 - A pretty special song and will revisit and relisten often.
5/5 - Can't stop listening.