The walls were supposed to be dumb. The losing war has destroyed the moral and economy of the world. The politicians created the wall as an excuse that they were doing things, even if it wouldn't work -- they had given up on winning.
No like, it's so dumb because the length of the pacific coastline is such that nobody would have ever even proposed something so outrageous. That would 135,663 kilometers of kaiju-proof reinforced walls, or 84,297 miles for those using imperial units. If we conservatively assume that you only need to protect 30% of the coastline, because Kaiju are fundamentally lazy and only use direct approaches to targets, that would mean building a wall the length of the entire circumference of the planet Earth. And not any old war designed to keep the mongols out, a wall that is so tall that 100 meter+, 3000+ ton monsters can't break through it.
I guess the fact that this was the "easy" alternative, the equivalent of the government alt tabbing into a spreadsheet to make it look like they were doing work when their boss walked past speaks to how utterly, laughably absurd the Jeager solution actually is. The largest construction project in the history of humanity is what you've done just to waste time and boost morale? LOL ok. Whatever you say.
All of the world building and explanation that has been provided to explain why the only viable solution is to build the world's most indulgent rockem sockem robots are mere band-aids on the stupidity. An actual solution would involve an interlocking series of defenses, early warning stations, huge heavy lift aircraft firing specially built munitions. The same stupid-arse rockets that the mechs shoot maybe? Or even bigger? Flexible, responsive, and much cheaper. Plant giant arse, super heavy duty undersea mines. Plant 5 kilotonne underwater mines above the damned spawn point. The pacific ocean is unfathomably large, we can write off a few dozen kilometers of it to keep us safe indefinitely. The Jeagers are a monumentally wasteful and inefficient solution to something which is, itself, a monumentally wasteful and inefficient mode of conquering something. The precursors are threatening not because they are ingenious, or because of their high level of technology. They're threatening because the script says they're allowed to have infinite monsters and just keep sending them through forever, at an accelerating rate. I think we can all agree that this is basically cheating.
This doesn't make Pacific Rim a "bad movie". However, it is indeed very dumb.
They require a lot of force to be able to pierce the kaiju skin, so they have to be launched at point blank range.
You do understand that it's normal for a cruise missile to break the sound barrier, right? That's a lot of force. If you strap a rocket motor you can go even faster.
