Like aside from the sorcand druid
Is there a unique class specific items that you CANT use at level 42 that beats out the lvl 42 version...why are the exceptional uniques superior to yhe other elite ones? And for what reason is it better?

you're right, most of the exceptional class specific uniques are quite good, but e.g., ts>titans in the new patch at least dps-wise

It seems like Blizzard wanted the exc version to be a good all around item for the respecting class. I.e. mass stats and mass skills. They did a more or less (more less than more) 'good' job with that.
Whereas the elite ones are more build specific. But as Blizzard didn't know proper builds back then, they are mostly garbage.

That seemed to be my general conclusion but then I was looking and it's not even that. Like the one barb helm has 2 to barb skills and masteries with life replenish and fhr. Arreats has more skills more res, more fhr, stats like damn they really dropped the ball. I feel it makes leveling chars boring and that's why everyone rushes chars because you hit 42 and you have your end game item. Be it arreats, titans,homu, hoz. Like you lose the level and upgrade as you go it's like 67 is the next level you MIIIGHT change the gear lol