There have been some truly horrific examples of what can happen to babies (lap children) in an aircraft emergency. However, even routine turbulence can have a negative impact on adults not strapped in. (Many, many injuries to FA's in the line of duty while not strapped safely into their jumpseat and to psgrs who ignore the warning.)
I believe that tickets for children 2yrs. and under are 50% off. These should be purchased and car seats brought along for inflight use. Any person traveling alone with a baby can get assistance from a skycap (please tip a buck or two) to the gate and always get assistance from a GA upon boarding if it's needed. (You won't be pre-boarded in most circumstances, but you will have assistance.)
It should be a policy. (and- I hate that word!)