maybe its a north american thing?
I mail things like cookies to people (my online friends, grandchildren, children, family) during the holidays (along with other food items) or for special occasions like when my brother was in the military...
For mailing I always freeze cookies and pack them frozen surrounded by ice packs and that way they survive the mailing better and are still fresh by the time they arrive.
I also like to have snacks, like cookies, in the house for when company drops by unexpectedly etc. And having some cookies that can be grabbed from the freezer and quickly thawed is just a nice thing.
If you were to make cookies just for yourself you could only eat one or two straight from the oven.
After that you're just going to be eating room temperature cookies.
You can always freeze cookie dough and thaw the dough prior to baking and on occasion I do that too but it's not practical in every situation such as the one you're in needing 300 cookies at the same time.