I thought it was a feature at first but now I doubt it's intentional as in my case it takes a few attempts to even open them, they just collapse in a millisecond. I'm sure devs don't intend for us to keep pausing the game to try to read our more impactful moodlets. Same with notifications if, as I suspect it's linked. Where it just flickers and shows and old notification.
With the moodlets I'm noticing it more with several. For example when they first get up in the morning and only have 2 or 3, they are all open. Then as they carry out actions, interact, eat, take a shower, more moodlets are obviously added. I've got used to ignoring them but it became more of an issue if for example I get random sad moodlets at the end of the list and opening it to see what's making them sad takes pausing the game and trying to prise that blue line open while it just collapses immediately. Same if I'm exploring the jungle and I want to check for curses/blessings.