I sometimes need (maybe 8-10 times per year). I can just pay for it, but the biggest issue is that paying in many airports is extremely complicated. Yes, in HEL it is very simple, but last time in NTE it took over 30 minutes. I challenge anyone to do it in FCO under one hour. There are many outstations, where it takes easily over 20 minutes. Just having luggage allowance in means that process is super simple and fast.