[61] The game was the first main - series Final Fantasy game to not include any compositions by original series composer Nobuo Uematsu. (en.wikipedia.org)
My gut tells me the restrictions for Dragon Quest Heroes have to do with JASRAC; Dragon Quest series composer Koichi Sugiyama is a council member for JASRAC! (kotaku.com)
It should come as no surprise that the key ingredient to the soundtrack's roaring success is the return of original series composer David Wise, who made a triumphant return with Tropical Freeze after an extended hiatus from scoring mainstream titles. (miketendo64.com)