I missed 1-2 weeks a year from school every year when growing up. My dad's factory had shutdown weeks when all holidays had to be taken. It was always in term time, and the fortnight one was in June. So, in order to be able to holiday we (me, brother and sister) missed school every year. This did not mean my parents didn't value school and education - infact they very much did value it!
However, they also understood the need for us all to have time away from the stresses and strains of every day life, having time out together as a family, time to be together and do fun stuff, no work, no housework, no chores.
All three of us went on to do well at school, passed exams, went to university and all working in chosen professions. Our education did not suffer at all. Our family life very much did benefit from family holidays, even if only a few days away, a few miles away on a beach.
It has to be a balance imo. Yes, school only occurs 39 weeks a year but as travel companies dictate the such high rices in school holidays, and people have mixed family make ups with family living abroad, etc. schools SHOULD be allowed to use flexibility and discretion.