The problem with the all in one basket approach, "man" goes and earns more and fixates on that position is what if something goes wrong. Business fails, gets made redundant etc
Suddenly you go from one supporting all income to none.
If both carry on working, maybe both end up behind their potential career due to family pressures.
If something happens to one of them, at least the other still has income.
You can if you need to pull out of nursery etc to reduce bills.
Having been and seen the nursery vs home schooling side, I am pretty convinced that nursery is better for all but the most effective parents in regards the pre school education.
When we talked to schools their main issues in regards being ready for school came from those who hadn't been to nursery.
I think this was partly behind even the stay at home parents getting their kids into nursery part time, that they got some pre shool education, routine, regiment etc