Hi HYEDID,
The reason that in the activity tab you see the names of different customers for each specific activity is because an activity is specific to one customer or a lead.
A campaign thought is not specific to one customer or lead, but to a big group of potential customers or leads. That is the reason that in the existing campaigns list you don't see a column for "Contact/Name/Company" as you would see in the existing activities list.
I hope that this helps.
Ronen