>>46554222>>46554264>>46554400The first half of the game is a mix of setup for the climax, and a "coming of age" challenge bestowed upon the player by Norman.
He sees that you're out and about with a Pokemon of your own, a true sign of imminent independence and more or less indefinite departure from home, and he only wants to make sure you're more than ready for the world, which is why he tasks you with getting four badges before you can take him on.
Once you best him, you've done it. You've proven you're all grown up, and the world's your oyster, made all the more evident by the fact you get Surf immediately after, thus truly opening up said world.
You're no longer the little kid getting a favor from Mr. Briney, you're the up-and-coming adolescent with a clear goal and father's approval.
It's exactly that kind of go-getter independence that inspires Wally right from the start to be like (You), and it comes full circle when you finally meet him out in Victory Road.