Cameras would be an excellent idea but for two things. For some reason, Aviation authorities appear to be unable to certify anything from a third party within a reasonable period, always deferring to the manufacturer for approval which gives rise to the second reason: The sheer greed of the manufacturers. The appear to be unable/unwilling to allow any modification unless they get a HUGE cut, thus making worthwhile ideas like this too expensive.
PM
Examples: AOM changes which increase an aircraft's operating envelope. A piece of paper that costs thousands to obtain, for each airframe. Or adding a "standard" EGPWS callout at $5,000 per call per airframe.