[0.982] UI issue - two tooltips for traits

I just realized something which is kind of obvious at first but at second thought it doesn't make sense.

Each trait basically has two tooltips. One that shows "all the time" and one that is shown when a hero levels up. Take Path of the Assassin for example.

This tooltip shows up in level-up view: http://i.snag.gy/4f3WF.jpg (also available when I hover over traits in level-up view at the bottom bar)

And this tooltip shows up everywhere else (unit details in example): http://i.snag.gy/NdP8V.jpg

So my question is... WHY are there two versions of all the trait tooltips? Wouldn't it just make more sense to just show the same everywhere? I mean the trait descriptions are good. They don't take longer to read than reading the second type of tooltip. And of course every now and then they differ in content - path of the assassin has information that it gives you access to assassin-traits in one tooltip, but not the other.