I honestly think it has nothing to do with not being royal any more. She is obviously dealing with a lot of negative posters and they have got to her. She is human. Look at how many people on here alone who have suggested the divorce is because she is cheating. Or for many other negative at her looks. She has basically got all the blame from many people. She wouldn't be the first person in a divorce, even royal, to speak out. If she is getting plagued with people saying 'why are you using princess, you are not a princess, stop using it....' to be polite, she may finally have just said 'okay lets shut them up'.
Her life really has not changed. She and Louis were not working royals anyways. She continues her charity work and life she had prior to marriage. It doesn't seem her life has been effected too much. Considering she had no title or royal roll for years after marriage, she obviously didn't marry for it.