For numerous reasons. For a couple of them, it’s not hard or overly expensive to assemble a home theater that sounds better than the local cinema. It’s even possible to get a better picture than the local theater, although that does take a bit more money.
In addition to better sound quality, you can watch a movie anytime of the night or day, not just when the theater is open for business. You can stop the movie to go the bathroom or get a fresh batch of popcorn, if you like. Or back it up to replay a section if you didn’t quite understand what the actors said. Also, you don’t have to deal with noisy teenagers with cell phones. You can use the HT system to enjoy more than movies – regular TV shows, sports events, and so forth. The movie theater doesn’t show soccer games.
HTIBs, while better than no surround sound at all, can have their problems and limitations. Many are not reliable – typically the DVD player is the first thing to crash. Since many HTIBs have minimal inputs, you can’t connect a separate DVD player, so the system is at that point useless. Speaking of minimal inputs, many people have problems connecting game systems like Xbox to a HTIB.
In addition, most HTIBs are low performance systems, their weakest point being their little “subwoofers” that can’t get anything close to deep bass.
While marginal performance is the downside to HTIB’s, complexity is the downside to a high performance HT system. Unfortunately, the better the home theater system is, the more complicated it is, so proper set up and calibration will always be an issue, initially.
Regards,
Wayne