[Klathmon]

It's not a "protocol" maximum, it's the currently allowed max in a lot of node software, since it's still VERY new and the probability that it will have a bug forcing you to lose all of your money is high right now.

So the developers put a limit of .04 BTC to keep that risk lower and prevent over-zealous users from losing a ton if something goes wrong. As the code matures and the network grows, that limit will be lifted in client code.

It's basically a "you can only easily lose this much money" max while the software is new. And you can compile it yourself without this max right now if you want to be a crazy person.