Go to University to have fun? it should be a place of serious learning, your there to work hard and get a Degree.
Out in the real world of work I'm sure your employer won't be telling you to have fun, he wants a good days work out of you. Every place I have ever worked if you look like your having fun the boss would soon find you a job to do.
You can have fun and still work hard. Some of the jobs I've done were drudgery, but others were interesting, fulfilling, and enjoyable.
One of my children went straight to Uni from school, the other did a vocational course and then went abroad to work at 19. She went to Uni in her 20s, by then it was the only way to get into nursing. She wasn't particularly academic at school, but was determined to be a nurse. She studied in London and enjoyed her time there. No degree, but a nursing diploma was all she needed. She eventually did the necessary (whilst working fulltime) and got her degree at 40.
The one who went straight to Uni had a good time too, his sport was important to him and that was a big part of his life there. After a year back living at home, and in a crap job he got on a masters IT course, and the rest is history. I agree with BL, it is great personal development for young people. I'd never grudge anyone the opportunity, however I'd be discouraging taking some of the degrees on offer these days.
If the grandchildren want to go to university, and they have the abilities, then their parents will support them. But if they want to an apprenticeship, or go on a vocational course, they'll support that too. Just depends on their abilities, and what they hope to do.