The person who makes the Satoshi client releases just seems to have that kind of power, especially when intimidation is added such as "you have to upgrade to 0.8 before may 15th". It's important to have some independent people look at the code of a release, so the community can be warned of any problems before the deadline.
I also stumbled on the piece of code mentioned here. This piece of code is clean: it is clearly necessary as part of the uncontroversial BIP 30. If you first read BIP 30 and then the code and comments, it becomes clear.
I'm having trouble understanding main.cpp. I think it's a huge mess, and potentially full of vulnerabilities. I've been following the development of the source code for some time, and readability is generally improving, but this piece definitely still needs lots of work.