There's been quite a few requests recently (by myself) for more leagues to be made playable on future editions of football manager by default
in a thread requesting the Estonian league be added @michaeltmurrayuk stated the following are reasons why leagues might be added
I think the 2nd reason (commerical sales) is something we as the fanbase on the forum can help the team at SI with by having a poll on which leagues would make us more likely to purchase the game (I'm always surprised by how many people are a couple or several editions of FM behind the most recent one) if they were added. When voting in the three polls I have created, you can select as many answers as you like, but think carefully about whether that particular league would have an actual effect on you buying the game. Some will, but not all of them. If there are leagues I have not mentioned (I went by the strongest leagues not featured for the two countries questions) then feel free to mention them in the comments.