That aspect is worth commending.
As is the fact that you can unlock most new stages with FM.
But overall the fight money system is poorly thought out. The vast majority of FM is locked away in single-player modes, or easiest to obtain by yourself (the 5k weekly quests), which means that it fails to motivate engagement with the main component of the game.
Compare SFV's fight money system with, for example, Heroes of the Storm. HoTS rewards you for playing the main modes, for playing with other people, encourages you to try different characters and modes via daily quests, and also allows you to purchase in-game characters with fight money.
And the range of items unlockable via fight money in SFV is rather lacklustre. Other than the stages and characters, there is one costume to unlock per characters (story mode), and after that you have colors, titles, and profile decorations. In that regard both IJ2 and T7 greatly outclass SFV.