Yeah uhm. The only reason a little tan is "healthy" is because according to people's beauty standards, when you're a little tanned, you look healthier. But that's just as true as those women from 500 years ago who bleached their skin with chemicals and were told it was healthy. Oh yeah, and there's also the fact that when hit by sun damage, I think the body releases some sort of euphorizing hormone, like it does with more obvious injuries.
You might also hear that seeing the sun is good because it produces vitamin D. It's true. However no remotely moderate amount of sun exposure would give you your recommended daily intake, if I remember well. Not to mention it's visible light that makes your skin make vitamin D. Not ultraviolets. Which means even with SPF 300 (assuming it exists), you'll get the very same amount of vitamin D produced.
The very reason you tan is that your skin was damaged. It says "never again!" and brings up some protection. Which is pretty ineffective overall.
There is aaaaabsolutely no reason to believe a tan is remotely healthy.
Besides, staying white has its advantages. After staying coped in almost all day, every day, all summer, and wearing SPF 50 every time I went out for any considerable amount of time, my mother invited me to go pick strawberries on a hot day. I noticed that my very white arms actually reflected light. It was over 30 degrees with humidity, yet I barely ever felt hot. And putting my arms out in the mid-summer sun barely felt warm-ish. I didn't know it was possible to be so comfortable out in the sun on a hot day. Apart from the eyes. I don't have sunglasses because of my prescription glasses, and my eyes are over-sensitive to light. Sheesh. I must have looked like I was making a bad imitation of an Asian all day. To give you an idea, I simply CANNOT bear to watch the TV with the Christmas tree lit up next to it. Yes, those really weak LEDs. Oh yeah, and when I borrow sunglasses to make a ridiculous contraption of dual glasses in my mother's car... it's still a little too bright. The landscape, that is, not the sun. :p