The Khajiit helmet...I cannot really comment on why, but I can say that I don't mind it much. I am not talking about the concept art itself.
Using purely released information so far. I will say that I don't like most of the helmets I have seen. Some just look stupid and not because they are trying to hard to look epic.
I like these armors. http://elderscrollsonline.com/en/media/screenshots/619 Probably because the helmet is absent lol.
I don't mind these, but they are hoods, not helmets. http://elderscrollsonline.com/en/media/screenshots/573
These are fine. http://elderscrollsonline.com/en/media/screenshots/557
I don't like these.
http://elderscrollsonline.com/en/media/screenshots/325 This does not look like the Ordinator armor from Morrowind and manages to rid itself of the parts I felt made it cool. Clearly an opinion, just like the rest of my post. Jaw is too thick too. This is what it looked like in Morrowind. http://i.imgur.com/bR6tytl.jpg
Spoiler LMFAO! I found a drawing I did in the first page's search results. Lol wtf? I typed in Ordinator Armor concept.
Search results- https://www.google.com/search?q=Ordinator+armor+concept&rlz=1C1SKPL_enUS396US397&espv=210&es_sm=122&source=lnms&tbm=isch&sa=X&ei=S3uWUuaND4ThoASg-YKIBg&ved=0CAkQ_AUoAQ&biw=1366&bih=666#imgdii=_
My Actual art. http://th05.deviantart.net/fs70/200H/f/2012/179/5/4/shalk_armor_concept_full_set__by_albinodunmer-d559igt.jpg
Weird...
http://elderscrollsonline.com/en/media/screenshots/317 Don't like the helmet at all. The horns are laughably big.
I don't remember which other ones are 'safe' or not so I am just using official ones.