The more friends you have the more likely you will get all four kinds of gifts each day, and well as they might show up to support your matches. If they are on you level, then they are more likely to to get drawn with you in League or CL, and I have on rare occasion met a friend a level above in Cup.

Since you don't get any hurt from away friendlies anymore, I make friends with anybody who requests, but keeping in mind it might make a more interesting League next Season.