I gather from that statement that samplers and VSTi (what's that btw?) are generally of better sound quality than synthesizers?
To put it simply, Virtual Studio Technology Instrument is a term referring to software synthesizers (I should add VSTi is plug-ins that you can access from inside your sequencer aka DAW, as opposed to being stand-alone applications). Although not a few people point out hardware is more stable and more expressive, software is generally easier for you to handle. Also, if I go so far as to say that emulating real music by computer is a matter of having as many digitized samples as possible, software synthesizers have a superiority in this regard. A top-notch VSTi such as the VSL full edition covers every pitch on a chromatic level, a wide range of velocity change, many articulations (e.g. legato, staccato, sustain), different microphone positions, blah blah blah, but it reaches good 550GB. While it costs too much to develop a hardware synthesizer that has such a large capacity for some reasons, nowadays it's not uncommon for someone to have 1 to 2 terabyte hard disk space in total and a Mac or PC with large hard-disk drives can have it without difficulty.
By the same token, we can say software samplers excel hardware samplers in capacity. Sakimoto has an EMU hardware sampler but it has only 20GB space. While maybe 20GB was large enough when released, now its really hard to contain today's large multi-timbre libraries, ones including a wider range of instruments. With software samplers such as Giga Studio and large hard disk drives though, everything could be stored at once. Therefore, only when composers focus on hardware's sound and tone which they feel is more expressive and stronger, is hardware preferred.
Anyways, as I clearly see many people in this forum get sick of my digressing (all the more for my sciolistic knowledge and inappropriate terminology), I shall shut up.
Regarding Grim Grimoire, my major concern is who did what. Iwata has a more minimal and melody-oriented style than Sakimoto, and Kaneda has some humor, but who knows Abe or Kamikura. Some say they are nothing more than pale imitators, but I need a few more albums to confirm it.
EDIT:I found my post too terrible to keep it unedited.