Dickybee007, that's certainly a good idea, though would a standard bolt (the hole size on my bass is about 10.3mm in diameter) have wide enough threads to grip the wood firmly enough? These specialist thread things have extra-wide threads to help grip the wood to give extra protection against pull-out, so it would be nice to work out a suitable test to compare the tendency of the hex inserts against a standard bolt thread to pull-out over time.

Looks are certainly an issue in some situations. My Hipshot bridge covers up the inserts as it sits right on top of them, but in other situations, they are going to be exposed. That's where the hex inserts fall down.