I was an only child. My wife has a brother. We felt it was important for our children to have siblings to have the opportunity for sibling relationships in adulthood.
That all depends on the relationship between the siblings. I have 6 siblings and because of life choices we rarely keep in touch. My spouse is in the exact situation.
Why? Is it possible our busy schedules, ability to relocate, and less dependency on each other are reasons why this may not be as important as it was at one time?