It's not. There have always been people who have nightlife as an objective - a lot of them are younger travellers who may not have had as much opportunity to go places in the past. But there have always been those of us who go to see the historic sites, museums and galleries, gardens, scenic beauty , etc first. You're not alone just not as loud or obvious are the drunks.
Because more young people want to travel before bound with responsibilities (i.e. car, home, family, debt, full time job) - SO more "party places" will be popular as a result of this growing trend of young tourists.
I love to immerse in the local culture and see unique sights of each country BUT because of my party-nature, I also party hard (while I can and am young).
Nightlife is completely different than home though, trust me on that one. The crowd is much different, the style (i.e. here, everything starts at 10pm, we get kicked out by 3am - in Europe, nightlife starts at 1am and goes until morning) - and so many opportunities to meet people your age which I LOVE.
Everyone has their preferences, that is yours, and this is mine.
because most young peoples idea of a good holiday is all about sex, suntan and getting drunk on cheap booze. now this might not be your idea of enjoyment but at the end of the day the resorts need their money and so the holidaymakers dictate what is on offer. as you say not your cup of tea, so you seek out the quiet and cultural parts of spain, and the smaller and lesser known greek islands.
Not here lol