Being a "Baby Boomer" I can tell you that men in particular have always valued being attached to women. Most men aren't going to marry someone or even ask them out just because they are a "nice person"
The main things most men (initially) look for are physical attraction, friendly personality, great sense of humor, and an indication that she is also attracted to him. (This is usually done with some subtle flirting on her part.)
Ideally the goal is to marry someone who shares your same values, wants the same things for the marriage that you do, (naturally agrees) with you on how to obtain those things, and last but not least there is a (mutual) depth of love and desire for one another.
As for the state of marriage today; statistics actually show that couples are (delaying marriage) longer than at any other time in history. The vast majority of people do not get married after only knowing one another for a year or less.
Another statistic indicates it is (women) who initiate the divorce filings 66% or 2/3rds of the time in the U.S. Speculation is the women of today have better career opportunities and more financial freedom than previous generations. The more options one has the less crap they're willing to put up with!
I believe the number one cause for divorce is and always has been (selecting) the "wrong mate" for one's self. This happens for a variety of reasons including your assertion that some of them don't invest enough time getting to know their mate prior to saying "I do." Essentially they were shopping without a "list".
In other instances they have never really done any serious introspection thinking to figure out what it is they want and need in a mate for life. Happenstance or impulsive connections led them to wed
The number two cause for divorce in my opinion is people get married for the "wrong reasons". (They hit an age goal, an ultimatum was given, an unplanned pregnancy, all their friends were married, just got tired of being single, someone in the military was about to be shipped out...etc)
The number three cause for divorce is mates change. (Some commit "deal breakers" such as cheating/abuse, neglect/grow apart, stop wanting the same things in life or fall out of love.) It's not uncommon to hear someone say: ":He/she is not the same person I fell in love with."