I totally forgot about the races in MToF!
This sums up the contribution MToF has made to the 5e player experience. Since it's been published I've only ever seen one person make a character using it (Eladrin). I personally believe part of this is because it is the least conveniently laid out book in terms of player material. The PC bits are sprinkled throughout the book, devil stuff in devil chapter, fey stuff in fey chapter, gith stuff in gith chapter, unlike other books that collected Player stuff in one place. You can't just get a feel for things by browsing the races and subrace options like you can in other books, you just see one bit at a time, isolated and inconvenient.