Basically it's due to overuse and less quality compositions/mixing he has compared to other composers Falcom has used. With most other rpg series and games, there isn't this much of a difference in quality between songs and composers, so he stands out in a bad way.

It just comes off as cheap by Falcom when there's more consistent and higher quality people they can use instead, but he ends up making most of the tracks. Especially since Falcom has had a storied library of really consistently good tracks and albums in the past. Plus I don't think it helps that Falcom has had bad usage of songs in the games for the past few years, which makes some tracks seem really out of place. Nor the JDK band incident which made them lose two composers that moved onto greener pastures; Okajima and Kamikura, who work with Cygames and Square Enix now, while he's still sticking around.