I think there's a big difference between the problem of modesty and trendiness.
Spiked hair, earrings and baggy pants are all trends that will either change or these kids will grow out of. It's part of being a teenager/young adult. Granted, most of them will regret the piercings and especially the tattoos later in life.
I was on the fringe end of the Jesus movement in the 70s. Hair down to my shoulders, jeans that had more patches than the original material. I grew out of it.
There are a lot of freaky looking kids that love Jesus. And he loves them.
In our homeschool support group one can view a full spectrum of young adults. From the 'rocker' look to intense modesty to somewhere inbetween. The common bond of this particular group is Jesus Christ. They love Him and serve Him with whole hearts.
However, I have to admit I'm thankful my daughter is modest and wholesome in appearance and doesn't follow trends or extremes. She doesn't dress to entice but she doesn't cover up in mock shame either. Just wholesome. :o)
God punished most of those long haired Christians by making them bald.
I think you are absolutely correct.
Now, I'm not exactly the trendiest guy. My closet consists of suits for work, kakhis and collared shirts for school, and t-shirts and jeans for weekend wear. Somewhere between college and law school, my wardrobe got conservative. Of course, losing 100 lbs. in 18 mos. helped force me to buy all new clothes, and at my stage in life, they have to be business casual or professional. But it didn't use to be this way. In high school, I liked baggy pants and gelled hair. In early college, I bleached my hair (briefly). Dumb, stupid stuff I'd never do now. It was a harmless phase, albeit stupid.
There's a world of difference between baggy pants and shorts and letting them sag so that your boxers are visible to the world; a difference between a girl wearing jeans and wearin skin-tight jeans; girls wearing shorts and wearing short shorts. Modesty should not be confused with conservative dress. Bell bottoms are modest, but they look ridiculous. But, anyone who wishes to wear them may do so since it doesn't impact any moral issues.
One aside: I really wish girls knew better just how sexy modesty is. Girls flashing cleavage are a dime a dozen now. Summer on campus is a difficult time to try to keep one's eyes to oneself, but at the end of the day, looking at them is a cheap thrill. The girls who wear feminine yet modest dresses, blouses, and pants are absolutely beautiful. There's just some je ne se qua about them that the girls wearing scanty clothing just can't show.