I agree, that type of sequence has been done to death in the kaiju eiga genre, but interestingly enough, as I recall, it's only been done once before in the Godzilla series. In Godzilla vs. Destroyah, Koichi Kawakita uses traditional methods to depict the crab-form Destroyahs climbing all over Godzilla and spraying him with micro-oxygen. And while not a bad sequence, Kawakita ever the "rebel" just kind of throws it in there without any explanation, and it's really just a set-piece that stops the movie in its tracks. It's almost as if he's saying, "here, get a load of this". In Godzilla x Megaguirus, atleast the similar shot works in service of the story. I like how Godzilla uses any and all means to dislodge the Meganula swarm from his body, from biting and clawing, to tail-swiping them and crashing into a rocky out-cropping. Then he tops it off by blasting them all out of the sky with his beautifully-rendered, golden-red atomic breath. And, of course, Michiro Ooshima comes to the rescue with some enthusiastic and frenetic music.
Without question, "GxM" is a mis-fire, but as with every Godzilla movie, I still like a thing-or-two about it. That particular sequence is one of them.
"EVERYONE FORGET YOUR TROUBLES! ENJOY YOURSELVES!THERE'S NOTHING TO WORRY ABOUT!" - Gigantis The Fire Monster
"It was HUGE...It was...IT WAS LIKE A MONSTER!!! Suddenly the rocks rose...ALIVE!" - Godzilla 1985