The phrase is what caught me, really. I remember when people were trying to analyze the prequel titles, and looking for these patterns where Episode IV and Episode I had 3 word titles, and then Episode V and II both had 4 word titles, etc. I think that's probably more of a tangent than anything substantial.
I think the phrase has infinitely more significance than the word count. And I think it even goes as far back as Yoda saying it to Luke in ROTJ. He told Luke "When gone am I, the last of the Jedi will you be". That same phrase turned up in a couple of places in TFA, as well. It's used in the opening crawl, and IIRC Snoke also referred to Luke as the last of the Jedi, too.
Then there's the whole 'Balance of The Force' thing to consider. We learned in TFA that Luke attempted to establish a new Jedi order only to see it destroyed. The end of Return of the Jedi also saw the end of the Sith, and from what we've come to learn Snoke is likely a Dark Side of The Force user as is Kylo Ren. Both of whom do not appear to be Sith, but something else.
So, what is Rey? If Luke is truly the last of the Jedi as Yoda said, will Rey become something else? It's very clear that The Force is with her. But seeing how the Jedi failed in the prequels and Luke's new generation of Jedi fell, maybe Rey is destined to be something other than a Jedi? Something that this new Sequel Trilogy era, along with the Clone Wars have illustrated is that The Force is much bigger in scope than this binary situation of Jedi or Sith. We've also seen Dark Side users like the Night Sisters of Dathomir and the trio of Force users that were embodied on Mortis. There may be some light side users who are not Jedi, too.
These are some of the questions that I have to take from the big picture when you take this title into account.