I just dont like the concept of friendlies because they totally devalue international football. Less is more as far as I see it. The more internationals are played then the more meaningless games there are, and international football becomes less relevant.
I would scrap the nations league too personally. The only games needed are qualifiers, tournaments and summer warm up friendlies.
Cricket could probably do with cutting back on fixtures too if they want to avoid ruining the spectacle. Its a similar issue. That period a few years back where there were 3 quick ashes series made the matches feel so small