Why is it so important to have a normal period?

Depends. Normal cycles represent that your hormones and organs are functioning properly. Any deviation from normal cycles can be associated with a number of medical conditions which need to be evaluated by a doctor. However, patient's on birth control do not "need" to have a period. Birth control pills were invented to closely represent the normal cycle to gain religious organization approval.
? Why would you want otherwise? At 45 it is likely that you will soon be having no more and they may already be irregular.