Listen Tommy,
I have thought of that idea too, but look it this way. Let's say your level 1 and you have a level 4 friend. You will be able to borrow legend or superstar players? It doesn't make sence. Besides let's say both you and your friend are level 1. The chance would be liek 2/10 if somebody lends you a player from his reserves,not to mention his first 11.
If this idea would be included sometimes, everyone would get offers from other players to borrow. It would be like when you get an 0 token offer via negotiations. You will understand what I'm saying when you reach level 5-6
Besides, even if you email Nordeus they won't include the idea.
So that is how things stand...