Like you, I've noticed a trend away from dreaming as I've got older.
I guess the dreaming could be chemical or psychological, or a combination.
I think magnesium seems to give me vivid dreams and I've read as much elsewhere. I sometimes take a zinc/magnesium supplement in the late evening, as magnesium supposedly helps you with maintaining a deep sleep (it seems to work and hopefully that's not psychosomatic). When I do remember dreaming, and it's still pretty rare, it's usually after magnesium, sometimes after alcohol, sometimes after an event that was more profound or thought-provoking than usual.
As far as personal observation goes, unless you log your dream activity diligently, it is hard to be scientific about when it happens and doesn't, because the memory is so unreliable and often creates false, imagined connections between unrelated phenomenon. For example, it may be that if you are stressed you remember more vividly, rather than dream more vividly.
I have no idea if this is an old wives' tale, but loads of people say that if you are woken up mid-dream, you are more likely to remember it, and that we usually dream on and off, all night through, then just forget them instantly because we slept past the dream. If that is true, then it'd imply that the vivid dreaming is a symptom of your poor sleeping, not a cause.
Finally, I'm not suggesting you're stressed, but sometimes we can suffer from stress-related symptoms without actually feeling stressed. Which is to say that one can be stressed without realising it.