From perspective of someone who barely speaks japanese: I've been contemplating on getting ONE and if I were to get her I'd get her talk too because there are songs with prominent "talk" parts like Yoshiwara Lament and Beast dance or I could add "talk" parts to enhance the cover, I've been considering getting talk vbs of the vocaloids I own in the far future for the same reason. I'm in the minority I know but still...I would be very surprised if someone who can't speak Japanese bothered buying an expensive TTS IA voicebank for a few very short joke talkloid videos due to being unable to fully utilize the bank.
Even if IA is supposed to be her own thing ( not arguing on that part, it's fair, I think even her V3s sound nothing like Lia anyways ) well....I'd be pretty upset if in the middle of the song I used a talk and it sounds absolutely nothing like the singer and could be mistaken for somebody else, you can get away with it more in quick talkloid skits but when put next to one another it sticks out like a sore thumb.