Remember that there is oil retention and water retention.
You can have oily skin that is also dry--it is oily but does not hold water.
Take away the oil and your skin looks worse because you can see the dryness.
I have noticed this with my skin...anytime I remove oil by any method, my skin cannot hold a normal amount of water. I look older and saggier.
A little bit of oil makes you appear youthful. Oily skin doesn't have to look shiny. You can have oil in a deeper level that sort of plumps the skin a bit. Let's say you're 30 but you have a bit of oiliness that plumps up your face and makes you look 25. You remove the oil and suddenly you've "aged" 5 years.
The other factor is that acne-fied skin is riddled with inflammation. INFLAMMATION PLUMPS THE SKIN.
When I went off Spiro my acne came back. So did some of the oil, plumpness, and redness. Skin quality was worse but I looked a little younger.
Now I am on a new regimen that has reduced my acne again. Guess what...without the constant cycle of inflammation I look older and saggier.
I'm not invested in Spiro anymore, but I have done a lot of research on how it works. I highly doubt that it irreversibly changed your skin quality or permanently aged you. Compared to many other drugs its mechanism is rather simple and its scope is limited. It is far less powerful than Accutane or even your run of the mill birth control pill.