Are car under-seat subwoofers worth it?

High-trust r/CarAV threads are blunt about it: under-seat units like the Pioneer TS-WX010A and Rockville SS8P add noticeable fullness over factory audio and are excellent space-savers, but reviewers stress you'll 'hear it, not feel it.' They're a meaningful upgrade for fill, not a replacement for a dedicated trunk enclosure.