Damage to other unseen areas is a very good point around composites. I'm quite sure that over time, mechanics and repairers will get "burnt" over this (as in missing something), but that would have to be an issue with metal aircraft also.
I'm hoping for the day when more LAME's are trained to repair composites so as to bring down the cost of repairs. A mate had a 15cm round hole poked in the side of his carbon fibre aircraft and was charged $6,000 repair it!