I can't believe there's a debate about whether the primary point of the movie was to find Luke. It's not even arguable, it factually is. As others already stated, the crawl is solely dedicated to this point. It's all Kylo gave a fuck about all movie long. It's what Leia was striving to do all movie long which includes Poe's involvement, what brings Han into the fold and it's ultimately what they focus on in the end. It's not merely a McGuffin because the ultimate goal for both the Resistance and First Order is to wipe out the other side. The reason Leia desperately wants Luke is extremely obvious. Her conversation with Han mentioned that Snoke seduced their son to the darkside ergo, she knows that Snoke is a Sith Lord. Who in the entire galaxy was more qualified to deal with a Sith Lord? She believes Luke is necessary to cut off the head of the opposing army which is often the goal of generals in war to cause confusion and chaos within the ranks. The flip side is that the First Order needs to rid of this commodity because like Palpetine before Snoke, the Jedi were the greatest threat to his rule. It's true we don't see Snoke mention finding Luke as a priority but the guy has like two or three scenes and do you think he's allowing Kylo to exert all his time running around the galaxy on this errand solely because Kylo wants to? Snoke is his master, you can bet your ass he's ordered or at minimum, approved he's primary pupil and grand resource using all his time to find Luke so clearly it's a top priority to him.
In the meantime, Snoke has his own general to focus on the opposing army and that's where Starkiller Base comes into the fold. The resistance doesn't even know about this base until the final act of the movie, it's clearly the "B" plot thread of the film. So while the true goal of both sides is to wipe the other out, that's a larger plot that will flow across the entire trilogy while the primary theme that TFA covers is finding Luke.