It does seem kind of silly, but I can see a somewhat practical application:
You want to take your PC with you on business and hate the idea of a laptop (Thermally limited/small screen/small keyboard) You could easily hook it to a hotel TV.
You can then take it home and hook it up to a good graphics card for serious gaming, or for presentations at conventions. (Multi monitor) That said if I were to go with display presentations at conference, I would go with Cooler Master NR200P, NZXT H1 V2, Fractal Torrent Mini, or Dan A4 (provided you are NOT showing off the hardware inside the box) Otherwise I would go with a Lian Li Dynamic Mini (even if that is totally misleading because there is NOTHING mini about it.) or possibly a thermaltake tower 100