At least in theory these Samsung sound bars are supposed to adapt to the listening environment to more accurately render the intended surround sound. They also have various non-trivial inputs (including wireless ones) as well as support for additional real speakers and subwoofers which again might need changes for compatibility.
Of course they could be designed to be simpler and have whatever input device is used (e.g. the TV) handle fancy features like mobile phone support.
Sure, you could do everything through a static circuit and require things being fed with speaker wire. But if you add a microcontroller you're going to be able to do much more, get better sound quality, and protect your equipment. Do your speakers have batteries? Do they plug into wall? Either way you can better control power levels. Do you want to boost bass? Fix corrupted signals? Do you want to process signals from anything other than a bare wire?
Sure, you don't need a microcontroller in a speaker. But we also don't need them in our cars. You don't need them in your fucking kettle. But personally, I find them useful and considering how cheap they are it's worth the basically $0 increased price.
See my other argument. The issue isn't that there's a microcontroller in the speaker. The issue is bricking the device. Don't confuse the means in which a bad actor operates with the bad actor themselves. You'll never stop the bad actor by just banning everything tool they abuse. You'll end up with nothing.
Imagine your signal comes in degraded. Some extra noise on the wire because it is passing next to a faulty wire in your walls or something. You can then do a FFT (example) and pull out the noise and rebalance the signal. Maybe an easy way to think of this is with radio since you're very used to dealing with static in that domain but fundamentally there's nothing different than signal coming through a wire other than the technicalities of the medium through which it's transmitted.
There's much more signal processing you can do besides FFT btw and many can improve signal quality and thus sound quality. Even something like a built in equalizer. Sure, you can do this all with hardware by creating all the right filters but you can do more in a smaller package with a computer
