Mark text message as unread

WHY after all these years and updates can we still not mark a text message as 'unread' after opening it??? I use this feature all the time in my email but these days work and personal contacts text me instead of emailing. Once I open the text, sometimes by accident, there is no way to mark as 'unread' so I can get back to it later (like when I am home from vacation) so I don't forget about it. I shouldn't have to go through the trouble of emailing the text to myself just so I can get back to it later.

Has anyone figured out a way to do this? Why doesn't Apple do this?