What Reasons are there to Make Summoned Units Special?

[Map Designer]

I can only think that it is easier to see and edit the unit properties. Is there any more reason?

is it a problem if I made an ability summon Regular Unit which isn't categorized as Special? am I missing something here? Thanks!

 

[Wrda]

Well yes, you answered it yourself, it's really the only reason. Just like there is a category for campaign units, so you can distinguish them from the rest.

 

[Zepher]

I think it's just done for categorical purposes more than anything else, so the programmers can have an easier time differentiating normal from special (summoned) units.