I do agree with you in theory, but also consider we didn't have a need for upward-firing/height speakers until Dolby Atmos became more mainstream, so there are even times (while less rare I can admit) that speaker upgrades/replacements are needed. Also, these types of powered speakers, for someone like me renting an apartment in Tokyo where I can't cut into the wall to run speaker cables nor do I have a stealth way to run wires to rear surround speakers, are a great option.I don't mean audiophile-grade. Half the price of a few basic sonos products will get far better sounding speakers and a receiver. And that better sounding setup will be far more versatile in terms of what you can play on it.
And when new formats/wi-fi standards/etc come along, you can replace the relatively inexpensive receiver and the speakers will be good and up-to-date for literally decades. And given that, I feel better about splurging more on those speakers.
So, it really is a "to each their own" situation, but a more high-end soundbar setup (as oxymoronical as that may come across) is quite attractive for people like myself who need that combination of quality/convenience/aesthetic that companies such as Sonos/Bose/Apple offer.