Do you think that it is legitimate to neglect a little more of your family life to access a higher position or to run a larger company?

NO, balanced can be created. If a person is not able to create balance in both then i my opinion he/she should not be on this position. Because if someone cannot create balance in his/her personal and professinal life how come they will be able to create a good balanced environment in company.

You must have work life balance to be an effective human in terms of profession and person.