1. A lot of jobs are "BSN preferred," not just jobs in management and public health. There are all sorts of jobs in nursing in areas such as infection control, case management, diabetes educator, ostomy coordinator, lactation consultant, discharge planner, research coordinator, project manager, patient educator, etc. etc. etc. etc. for which a BSN is an asset. You may see some people without BSN's fulfilling these roles, but an increasing number of employers
are preferring to fill any positions beyond the entry level staff nurse positions with BSN-prepared staff.
2. Some people simply like the additional depth and breadth of knowledge that is available in a BSN program. (Though I readily acknowledge that a poor quality BSN program does not provide a better education than a high quality Diploma or ADN program. But a good quality BSN program should provide the best entry level education if all other things are equal.)
3. Some people are considering getting a graduate degree, for which a BSN is a necessary step.
4. Some people are committed to helping the nursing profession gain the same status within our society that other health care professions have, which will probably require the BSN to become the minimal entry-level degree to qualify for the professional role.
That's just a few reasons off the top of my head.