The film's a freaking mess. Raleigh Becket is the most boring protagonist this side of whatever it is that Ethan Hawke did last, because he starts out a cocky hotshot who hates Kaiju because they killed his brother, and he's the exact same when the movie ends. You can argue that maybe he learns the value of cooperation as evidenced by that "let's do this, together!" line, and he learns to open up to Mako Mori, but if you have that opinion you're stupid, so I can ignore it. Raleigh has less depth than the useless secondary antagonist's dog.
But all that's fine, because I figured out ...
How to Fix It
Switch Mako and Raleigh's places in the story.
The opening of Pacific Rim is a voiceover explaining how the world has Kaiju now. Then, bam, we meet two characters, brothers Raleigh and Yancy Becket, as they pilot their Jaeger against a Kaiju off the coast of Alaska. Yancy is killed, but Raleigh manages to kill the monster. This is not how Pacific Rim should have started.
The best scene in the movie is a flashback at around the halfway point, when we see Mako -- as a sobbing child -- running through the smoking remains of Tokyo as a huge crab Kaiju barrels down on her. Just as she's about to be squashed, Stacker Pentecost shows up and saves her. This is how Pacific Rim should have started. Mako should be the character we meet first -- as a child -- and Raleigh's tragic backstory should be revealed at the halfway point instead.
This works better for a few big reasons. First, Mako is a far better protagonist than Raleigh is, because she's a synecdoche for the human experience of encountering Kaiju and therefore a better surrogate for the audience. If we're introduced to her as a child, we follow her (and humanity) from naive and impotent terror, to aspirational self-improvement, to triumphant vengeance. Bam, fools: Hero's Journey, all up in this bitch.
Allll up in it.