Regarding lap children, driving is far more dangerous than flying, and as nsx reported, the FAA concluded that it's safer to allow lap children. Many people would rightfully fight a change to the rule.

Regarding overhead bins, just today on flight 243 from JAX to IND, I had my 22-inch Samsonite roller bag stowed front-to-back (top handle facing out) on a -300 aircraft, and after I sat down, the rear cabin flight attendant walked forward and rotated my bag so that it took up more bin space.

When she walked back, I said, "My bag fit the way it was." She said that it didn't look like it would fit, and I replied that I had closed the door to verify it. As more passengers boarded with their bags, she went back and re-rotated my bag so that another one would fit in the bin with it. She then came back and we had a nice chat about how it fits long-wise in the -300s and -700s, but not in the -500s or -200s, and then after seeing my cool pleather lanyard she asked if I worked for the airline, and we had a pleasant conversation thereafter.

I maintain that bin space is often mismanaged by both passengers and well-meaning flight attendants.