I doubt she meant removing personal bias, since that's obviously going to be present no matter what. I think it's more biases in the scores themselves, skewed toward certain numbers due to the presence of Other.
Something nobody's mentioned so far is that we could just adopt the scoring scheme used for LL LDCs, 25/20/5 (a 5:4:1 split between fun, graphics, and other), which places the emphasis on the key aspects of the level (main two categories), places marginally higher emphasis on gameplay to placate you guys who insist that it's objectively more important, still gives atmosphere a significant focus, has a small catch-all category for anything else which isn't so small that it doesn't make a difference but also isn't so big that it leads to major bias in the scores, and uses nice round numbers for every category, with an overall maximum of 50. We could even scale that down to 20 overall by multiplying everything by 2/5 (after the fact, though, since otherwise judings would be 10/8/2, which is even less pretty than 12/8 or 15/10). And if you want, we can keep the new "Atmosphere" name instead of Graphics.
Honestly I hadn't thought about doing this at all until I reread the OP just now and noticed Shroom's mention of it at the top of the post. But it seems like it could potentially be a better option than the current 10/5/5 (2:1:1) system or the proposed 2-category system, whether 12/8 (3:2) or 10/10 (1:1), taking aspects of both systems while maintaining a balance and allowing room for extras. Best of both worlds? Though there's still the issue of re-scaling past LDCs, but that's an issue with any sort of change to judging standards.
What do you guys think?