-Easier birth control: Make the egg into an omelette
-Relaxed child support laws: Requires deliberate decision to incubate the egg
-Clean packaged periods: Egg = No mess!
Although, there would be stories about partners hiding fertilized eggs: Instead of unplanned parenthood we would have unconsensual parenthood
There’s probably more nuances I am missing. But do discuss it in the comments.
The more you know. So it could be more likely that humans sat on their eggs to keep them warm, or they would have been limited to tropical climates. Humans would have evolved very differently regardless.