Once again, Linus getting grumpy leads to neat stuff. Picking a defconfig file for a bare ARM chip brings in too much useless stuff (someone else's choices for SLAB allocator, LCD support, etc). As the article says, it's rare to use one without changes. Heck, how many people use the default x86 kernel config without changing something before compiling?
In fact, I think "make menuconfig" should save the set of "local overrides". This file could be copied from one kernel version to the next, instead of the entire .config. It will also make it trivial to see what things you've messed with.