...The only reason Maxwell has been pushing side chains (if you follow the arguments from the beginning) is because they would allow needed features without bastardizing the original design of Bitcoin. If you're going to change something as fundamental to the original design of Bitcoin as block size why don't you just increase the max coins above 21m or lock the mining reward at 50 coins? The only way to change a basic core design feature of Bitcoin is to admit that the design is flawed. If that's the case then design a new coin that's not flawed, implement all of the corrections you want to the new coin and end this failed experiment. To me this argument is no different than PoW vs PoS. You can't fix that midstream. You need to start over.
But the 1MB limit wasn't part of the original design.
Here, Gavin explains:
Back in 2010, after Bitcoin was mentioned on Slashdot for the first time and bitcoin prices started rising, Satoshi rolled out several quick-fix solutions to various denial-of-service attacks. One of those fixes was to drop the maximum block size from infinite to one megabyte (the practical limit before the change was 32 megabytes the maximum size of a message in the p2p protocol). The intent has always been to raise that limit when transaction volume justified larger blocks.