An HTIB will give a better listening experience, but it still is best to select one that has conventional non proprietary speaker connections to allow for speaker upgrades. The difference would be night and day even if only the front mains and center were upgraded for a start. Many people do that and then add the matching satellite rears, sides, and/or better sub. The smaller HTIB speakers "work" but it's almost overkill to have all the latest sound decoding capability for movies and funnel them through the tiny HTIB speakers. Also, even with one listening position, getting a good stable sound setting with HTIB speakers may be nominal and room acoustics, objects (or moving them) in the room, furniture, and other things can have a large effect on any mic/cal settings. Standing waves and room resonances are usually tough to deal with in a room used for general living quarters. So many times a compromise and even turning your head while watching a movie can sometimes reveal these annoying audio artifacts.
All that said, of course even a 2.1 computer desk top system makes TV speakers sound puny. So it is all kind of relative to how immersive a person wants to get, space allows, or apartment or condo neighbors will tolerate.
I guess I am more particular about sound and, while I haven't spent the gobs of cash for the mega buck systems some have, I do miss the enveloping sound I have at home compared to most store demo system in AV boutiques or other peoples home. There are systems I've heard that are to die for, but a person usually has to draw the line somewhere. Audio is a whole other realm of nuances, technicalities, and opinions.