When not using a DAW.
I am not a professional musician by any stretch. I wouldn't even really call myself a hobbyist. My primary instruments are banjo and guitar, and I play either one of them at least an hour a day in the evening. Usually more than that. I've only recently begun experimenting with synths and DAWS and drum machines.
So I guarantee arturia's products were not made for me...
But...I just like playing. Loading Ableton Live, launching the plugins, creating tracks and all that is a pain in the ass. I'd rather just launch Pigments and Spark and just start jamming for my own enjoyment.
My first physical synths were Korg's Volca series. I have the FM, Beats, and Keys, and more often than not, I find myself turning away from the much more powerful computer-based options just because it's tiresome to set up. With the Volca series, I sit down, create a basic beat, then a bassline on the FM, then fill in the beat the emphasize the bassline, then work out a melody on the Keys...and it's fun. I don't have any intention of ever creating an album or even sharing what I do with other people. It's just for my own enjoyment.
I would like to be able to do the same with Pigments and Spark. Except I'd like to be able to open two instances of Pigments, for bass and lead. Not have to use Ableton or any other DAW unless I like what I've created enough to actually want to record it or preserve it or whatever. (Oh, and I'd like to be able to record a sequence, rather than the way it's implemented right now.)
As I said, though, I understand that these sorts of tools are not really meant for me so much as for the professional musician/sound designer, etc...
Anyway, I guess the answer to my question is, "Only with a DAW..."