I've given up half of my trunk for a sub before. It is absolutely fun, but I never did it again after getting it out of my system. "lacking" is a matter of perspective. I had eyeball vibrating levels of bass in my Acura Integra, so anything else could be considered "lacking" comparatively. Previously, when I bought a car, I already figured I'd be replacing the entire audio system very soon. These days, the manufacturers realize a good system will appeal to some people.
IMHO, bass is not lacking at all in my Ioniq 5 either. Not with the "regular" system in the 2024 and definitely not in my current 2026.