The HRH status denoted a direct family connection to the Crown and is awarded or withdrawn purely at the will of the monarch. There was simply no way that the Queen was going to let Diana continue to bear this appellation after the divorce. Her concerns were that it was impossible to know where Diana's private life might take her. The implications of the withdrawal of this were that even lesser members of the RF such as Princess Michael of Kent, whom Diana apparently wittily referred to as 'the U-boat Commander' would take precedence over her, and that she would even be required to curtsey to them.
Diana initially agreed to losing the title because bigger issues were at stake, the main one being money. Sarah Ferguson had been negotiating her divorce just as Diana approached hers and the example of the former was uppermost in Diana's mind, as she had been well and truly bested by the Windsors.
If Diana had retained the HRH status she would automatically have been included in state occasions and properly acknowledged as the mother of the future King; however her agreeing to relinquish the style of HRH and then deciding that she wanted to keep it was useful in her tactics to secure the matter that was of great importance - her divorce settlement. Diana may have lost the style of HRH but she did win something far more important to her future life - financial independence.
In the long run, the loss of this style was no hinderance to her in the pursuit of the things that mattered to her. To the people who met her and whose lives she touched, she was always a princess, to some even an angel. Faced with the choice as to whether they would have preferred to meet Diana sans HRH and one of the many unappealing others who can boast to being styled thus, I think we can all imagine too well the choice that would be made..........