That's just the impression you got, because by the time you reach 8-K you've practiced your skills to the point that everything seems to be much easier than during the first few hours of playtime. Play both levels in mirror mode and you'll see that 8-K is the harder level out of these two.
Regarding my question to Resident_Hazard, I've found the answer coincidently in a thread from 2008. He really is claiming that Metroid Prime 3 is dumbed down based solely on the normal difficulty setting which is an easy mode that wasn't present in the first two games. Normal in Metroid Prime and Echoes is the equivalent to veteran in Corruption, but he barely touched that (didn't even play up to Mogenar).
Claiming that a game is easy based on easy mode... well, that's not conclusive proof.
Not really. I only unlocked 1-K after beating through world 8, then went backwards to get all the letters. Did world 1, beat 1-K, then went straight to world 8, cleaned it out, and did 8-K, so i was comparing them within a day of each other, and i had a much harder time adapting to 1-K's demands than 8's
Monster Hunter: pissing me off since 2010.