Why Arcane Surge?

I saw this on multiple charakters.
I think even Palsteron had it on an early version of his build.

But why? There i no linked Spell that deals damage and no Mana Regen.
Is it just because of Arcane Blessing? I wonder because only 27% of these Builds use that Ascendary.

Arcane surge still grants 20% cast speed to all other skills plus the mana regen.

It has very good benefits, as mentioned above. It is attached to arcane cloak because it ensures a good uptime on the effect, without having to attach it to your main attack skill, which would use up a valuable socket in your 6-link.