Every team needs a good free-kick taker.
Without one, teams won't feel threatened when they concede free-kicks and, therefore, won't be too worried about committing fouls that can break up a good passage of play and relieve pressure.
Furthermore, a good free-kick taker allows a side to make the most of what is, essentially, a free shot on goal or a free cross.
Some teams are lucky enough to have more than one player capable of taking good set pieces, others have none. This means that while this is a top 20, not every team is represented.