I think Haakon and William both married women they found stable inside and would make good mothers and partners.
Neither woman seems overtly in it for the role. Yes, to a degree, but more the man and the marriage.
I don't think that MM and Kate compare well. I think Kate just lived the blueprint life of an upper class person in the UK: starting with having a conservative name, attending private schools, not doing much, focus on marrying well. MM went down a lot of dead end roads including drugs, being a single mom, endless partying, living on social welfare.
Initially they both started of incredibly slow. But there was a development in Kate. We never saw a lot of development in MM, really.