Isn't around 80 cd/m2 really dark?
It doesn't work the same way across all displays. 80 cd/m^2 will still look good if the display is optimized for that range. NEC is optimized for something closer to 120ish, although that's too bright for a lot of things. It's just easier to control if you have a low max brightness and dim room for minimal reflections. For photographers, graphic designers, etc, if they have to run inkjet proofs using something like EFI or GMG, most don't own the huge color corrected viewing booths that cost upwards of $8k. Smaller ones are typical. These aren't that bright, so the lower brightness range is suitable. Actual softproofing systems are a bit different. Most of those recommend a very specific set of hardware that has to measure within a certain tolerance. A large viewing booth produces much more returned light reflected off whatever printed media, so their brightness recommendations are much higher.
In all cases it's just about control, and you cannot analyze whether something is bright or dark in an arbitrary manner when describing a completely non-linear representation of raster data on screen. There aren't many specific standards that can be easily applied by independent professionals, so it's easy to pick up what sounds right or not right from fragmented data. All I would really suggest is that if it matches the rest of your pipeline, it is fine, and that too bright a display can be far more misleading visually than one that is darker, assuming it still tracks the appropriate gamma per channel.