True, though there was often some kind of involvement (including permission, if only implied) from religion, commonly acting as a pseudo-government in such times. I do suspect there was a strong distinction between the wealthy and noble compared to the common people but that was true for many civil and legal issues.
If you're now talking about the present day, I think this is very much not the case - there are plenty of legal situations where a legally recognised marriage is relevant. It is certainly true that unmarried couples are more often recognised in case law and legislation for simple practical reasons but that is far from meaning marriage is legally irrelevant.
Really? I've never known of anyone suggesting any such thing. I've certainly seen people objecting to couples living together without getting married, but that is more often a religious/moral objection than a strictly legal one and I've not seen any "abusive man" angle to it.
I'm not sure that is practical. The point of many of the legal recognitions of marriage is abut acknowledging the commitment and the implied rights and responsibilities. I don't think you can expect the law to treat "married" people differently to "unmarried" people without any formal way to define the difference and I don't think you'd really want to entirely eliminate all of the legal rights and responsibilities being married brings.
I think in most developed nations (certainly here in the UK), getting a marriage licence is largely a formality, part of the process of ensuring the people involved are of age, consenting and not already married. I don't think there is any system of them being refused outside those strict legal restrictions (and even then, I'm not sure that would be caught at the marriage licence stage).
There are pluses and minuses both ways. I think the bigger difference is probably psychological with good or bad results.
Marriage with a marriage license to some people's mind means it is FINAL! as an enormous change in their relationship. This can bring reassurance and does make separating a bigger decision maybe. But it also can put a person dangerously in a comfort zone being so certain the relationship is permanent that they take it for granted. Ultimately, that conduct can ruin the marriage.
We were unusual because we married without a license in a full blown church wedding. Over 300 people. Flowers, dressing up, Attendants. All the post marriage reception stuff. Even breakfast and brunch the next day. Only her parents knew there was no license (her father the minister). I think the reason they went along with this is because they didn't think the marriage would last 2 days - and for good reason - and maybe really hoped it wouldn't too. That was about 2 decades and a lot of kids ago. lol However, they are wonderful in-laws and 100% positive towards me and supportive overall.
Later we did enter into a lawyer prepped contract on economic and children matters including in case we part ways. Signed. notarized.
Most married people without a license have no ceremony and no written agreement. Rather they just evolve or into living together and then it just gently becoming "common law" marriage to their minds. While this makes parting ways easier. But it also means there isn't necessarily are hard line (filling for divorce) if breaking up, maybe making it easier to reverse the breakup - and maybe not having the "assurance" of a marriage license will cause both to be more attentive to the relationship.
The divorce procedure can be brutal and massively destructive economically and psychologically, particularly with children. That can happen of course in common law marriage, but they are less likely to think in terms of winning (destroying the other) in court maybe too. I suspect without the brutality of the fight over the kids and over economic issues it could be far easily for an unmarried couple to maybe reunite or have a more working friendly relationship even if they don't.
I've seen so many people shattered via divorce court - and then put themselves back together, act like they should have kept acting while married to find someone else, and basically end up in the same type marriage with a new person - next marriage same as the old marriage - with all the residual anger and damage. Often the grass isn't greener on the other side. Then again, sometimes it definitely is or the couple just evolved in different directions.