If rebooting fixes it, and it's been up for a while, you should suspect swap fragmentation.

You can defrag your swap by setting swap partitions on both internal memory and SD card, and switch between them; there's some posts about this, search if you care. (Or if you have enough free memory, just swapoff/swapon your single swap partition... may have to close all applications to do it.)

But I didn't see you asking for advice, just ranting, so maybe this isn't what you want -- in that case, feel free to ignore it.