I honestly don't care who is added to the game at this point- the roster is diverse and wacky enough that I really can't think of another character I personally want. I have Shulk, R.O.B., Duck Hunt, Bowser Jr.... So any character added to the game at this point is just an added bonus that I'll enjoy in some form.
Square Enix deserves a Smash Bros. rep. It has evolved past the idea of "Nintendo All-Stars" and is now just a celebration of gaming, period. Square Enix has supported Nintendo with releases in the past and is doing so now. Now, there really is no more iconic Final Fantasy character than Cloud, so the choice seems obvious. With how on-and-off Dragon Quest's relevancy is in the West, as well as SE announcing Final Fantasy VII Remaster, the time was right and the logic is sound. Would I love a character from Chrono Trigger? Sure, but despite being one of the best RPGs ever it's criminally underplayed and not relevant at all.
What we need to understand is that most, if not all of the future Smash Bros. DLC is going to push for relevancy. They are going to want people who have not considered the console or franchise to rethink their purchase and maybe even its relevancy as a crossover fighter. Ryu, Cloud, Pac and Mega Man are all smart choices for that, and I expect that trend to continue.