If there were 30 overhead and underfloor speakers then some one would want it. Most people are happy with stereo or a soundbar. This is not a normal place, with normal people. If you build it, we will buy it, whether it actually makes a difference or not.
I've had 7.1 for over 15 years, currently I am trying 9.1, soon to be 11.1. I can't say I am noticing a measurable difference but it sounds nice.
Both Dolby and DTS have upmixers for any old sound formats which can improve things for the most part. There is even Auro 3D for some, whose system supports it as yet another option.
Atmos, Dts:X is largely the domain of 4K UHD discs however there are a few blurays with this format (hopefully growing). Those that don't usually have True HD or Master Audio.