They have already released many games on mobile platforms.
People are obviously buying and playing them, so it pays off for the developers. I wouldn't say the experience is much different if we're talking about older FF games like FF6, FF7 etc. Those were ported straight from the PC, so nothing was lost.
Newer FF games, however, are pretty much completely different games on mobile platforms like Android and iOS, so they are very much inferior to console/PC versions.