The full dynamic range is nice if you actually want to experience it and have a system capable of reproducing it. A dedicated center channel with a few hundred watts of amplification behind it will cut through the ambient backdrop like a hot knife through butter. You can watch Transformers or MI3 at reference volume with crystal clear dialogue if you're willing to throw enough power at the problem.

What really would solve the movie issue is there was more standardised sound across different streaming services. Every single seems to have a different volume and compression / setup.

That and having an industry standard way to crank the center channel (user setting) when downmixing to 2.1

I've always set up my center channel volume using the test mode (by ear many years ago, and more recently automatically with Yamaha's YPAO).

Am I meant to then override that by increasing the center channel volume so it's louder than the other speakers?

Or raise the system volume?