It's not just greed like other commenters might be implying. Like you say many reformulations happen because IFRA (the International Fragrance Association) upda

It's not just greed like other commenters might be implying. Like you say many reformulations happen because IFRA (the International Fragrance Association) updates their list of restricted or prohibited substances. Their work is necessary and important to ensure everyone's health. Just recently (March this year) the IFRA-imposed ban on Lilial (butylphenyl methylpropional) went into effect, which was suspected to lead to infertility. So it's important someone has an eye on this. Almost always fragrances end up significantly weaker after such reformulations. Also after the 80s, where fragrances were much stronger, it's just a "trend" nowadays to have weaker fragrances. Of course it's also greed, because very often fragrances get reformulated without an obvious external reason and they often end up a shadow of their former selves. If a fragrance has a critical popularity, you can simply cut it's potency in half and people will still buy it. I also want to add that the performance of a fragrance depends a lot on the moisture of your skin. Fragrances disappear on dry skin much quicker. So if you moisturize your skin before applying a fragrance, you will have longer of it. My skin got much drier with age (and it's getting worse), so maybe this is also part of what you are observing.