You're very welcome, thought-priest.
The "Backdrop off" idea was just for your exploration, to "see" what the rendering can "see".
Yes, those images can become large, and I have some HDRI (since I have loved to shoot my own for over two decades) that are much larger, 64K+ wide.
The small ones are more for lighting purposes only. Whereby only a very few in the Asset Browser are color precise, going by the light that would be expected, most of them are sadly color correct, easily swappable [sic], and lost, so they're used for my use).
My take on your question about washed out:
Washed out can have many reasons; often, little to no knowledge while developing those HDRIs leads to their limited usability, and I'm sorry that my input to the latest selection (in the Asset browser) was ignored. Hence the lower quality. I hope we can do better in the future.
Like a sunset is just more orange, one should expect a gray card to be gray then; things like that ruin it. In my opinion, one should always set up HDRIs. I use my Spectrum-meter (Sekonic C-800) and a light meter to shoot HDRIs. I do not trust 3rd parties, nor have I seen clear information about them. Libraries are for testing, to be frank. The worst case is Radiance (.hdr), which is a fake format 4*8bit integer, not 32bit/float/channel, and has pretty much the most questionable color management from all, meaning none in all cases I have seen.) so, if you can shoot your own.
Cheers