I don't know why you consider that a "half-fix".  The computer always boots to full functionality.  If you want to call it a "hack" or "kluge", I can agree with that. 

Here's my theory on why it's happening:  It's not a "dependency" per se, but a timing issue.  As the layers of drivers initialize, they return a "successful" status, even though the hardware really isn't quite ready for prime time, because there is nothing left for the CPU to communicate to the card to complete the hardware initialization. The situation is not unlike an application making a system call to write data to disk, which returns with a good status even though the data have not physically been committed to the drive's platters, as it may be buffered in RAM by the kernel, or shipped down the wire to the drive and sitting in another buffer there. The ifup being executed earlier in the init scripts is catching the card in this state, but when rc.local runs a few seconds later, the hardware really is ready to come out and play, so the ifup works.