That's all well and good for the safe-queen, internet-picture-posting, crowd, but those of us that shoot, train, and compete with the AK know better.
In running dynamic shooting events for the last 3+ years, I have yet to see anyone show up and be remotely competitive with a "KISS" AK. It just doesn't happen.
KISS is all well and good until you start shooting, moving, trying to make hits in reduced light, trying to make hits past 100 yards, etc.
Would I put a VFG, AR-style stock, etc. on an AK? No, but if they help the shooter get better hits faster, and don't impede the basic operation of the gun (VFGs get in the way of mag changes, AR stocks seem to like to come loose, etc.) then I say go for it.