If I recall correctly, I believe there are countries outside of the United states and Canada that do not recognise temple marriages has valid. As such, members have to be married civilly before they can be sealed. I also believe that such individuals can be sealed immediately after.
In the United States and Canada (at least), temple marriages are recognised as valid. As such, members are not required to be married civilly. Members are free to be married civilly previously to the sealing if the wish. The catch, however, is that such members have to wait a year from their civil wedding before entering the temple.
I am doubtful it’s of any eternal consequence since members in other countries can do it.
Is it simply a cultural issue?
I do not see what benefit there is in forcing a husband and wife to wait an entire year to enter the temple if they are temple worthy and devoted to each other.
Come to think of it, I’m sure if we had been married civilly first, some of our siblings would have been more pleased. Not to mention those who have parents who are not active members of the Church.