Know what you mean OP, but I don't think I'd describe people as more beautiful, exactly - more glamorous, perhaps, or polished?
People do seem to look better groomed these days. I think it's partly because, as others have said, there's a wider range of cheap, accessible beauty products, and people are spending time, money and effort on looking good. Because of the internet, there's also way more beauty-related stuff out there - endless articles about celebrities' preferred products/grooming habits; beauty bloggers; forums like this one to discuss style and beauty. There's a massive media obsession with how people look, and I think many have responded to this by making more of an effort. (In my day we had to resort to Mizz and Just 17 for our beauty tips!)
We're also getting more obsessed with clued up about our looks at a much younger age. I work in primary schools, and each year we send a cohort of fresh-faced, innocent-looking Year 6 girls off to secondary school. Almost inevitably, when they return to visit us six months or so later they've adopted the generic 'teen clone' look - permatan, spider eyelashes and straight highlighted blonde hair. Many of them are utterly transformed from how staff remembered them . There's a 14-year-old I know quite well (taught her a few years back and parents are in my social circle) who literally looks about 35 in photos. This seems to be a strangely British thing - DP and I were in France and Italy this summer and the teenagers there somehow managed to look stylish without caked-on make-up and overdone hairstyles (and they didn't all look the same).
I'm not even that old (34), but when I look back at photos of myself and my friends from the '90s I'm shocked by how much younger and more scruffy wholesome we looked compared to teenagers today (this was the grunge era, though, so I guess no make-up and scruffy hair was kind of the point!) As much as the invention of things like GHDs has been a lifesaver for me (my coarse, frizzy hair was the bane of my teenage years), I do feel a bit sorry for younger people today for not having the freedom to experiment and find a look that suits them - I look back fondly on my teenage encounters with Sun-In and glitter eyeshadow!