Completely valid point, and if Sparx wasn't played by Billy West then I think he would be completely insufferable.
I mean, I think there was some conflict between plot tone and writing tone. Spyro also does some quips and sassy comebacks, but because he's voiced by Elijah Wood, it just sounds like he's being all calm and collected. I think the Krome games were supposed to have way more humor to contrast the bleak lore, but the star VAs except for all of Sparx's held it back more than anything.
edit: wow, looking at dialogue from other versions since I never saw the DS games, and yeah, Spyro isn't supposed to be that soft spoken. Wonder if they started out with a less serious voice actor more like the Classic games.
Actual line from that start of ANB where Sparx gets eaten in the DS version instead: "Gee, I dunno, Frogweeds gotta eat too." Spyro absolutely tries to match Sparx in snark.
edit2: more classic spyro on the wrong game:
"Wait, was that Cynder?"
"I sure hope so."
"What?!"
"Well, if it wasn't, that means there's more than one giant evil dragon around here."