Not even arguing with your points but do you think shared custody should be the default anyway?
Women can and do move funny knowing the courts are gonna back them in most places.
I think if both parents are deemed to be competent....then it should be 50/50.
If one spouse has a more demanding job (investment banker, ER nurse, fireman etc), then they should adjust accordingly.
Child support should only come into play if there's a huge gap between availability. Example: wife makes $500k/year in a job where she works crazy hrs and travels a lot. Husband makes $150k/year but it's a low stress salary job. He agrees to take the kids for longer periods of time, but she gotta pay.
The whole quality of life thing should only matter if there's a massive discrepancy in pay. Like if both parents agree to 50/50 custody but one parent makes $$$$$$ while the other makes $$. Usually the gap ain't that big unless one parent was a stay-at-homer. It made sense back in the day, but women tend to make good money now.