Hehe what if almost every bitcoin trader, investor, and regular user would resort to coinjoin and mixing services?
That would be the dream. It would render all blockchain analysis completely useless, cause all these companies to shut down, and improve everybody's privacy significantly. Centralized exchanges already force KYC on everyone so nothing would change as far as using such an exchange is concerned
without any valid reason I don't think you really need to used mixers at all
Basic privacy is a perfectly valid reason. I don't want a bunch of complete strangers tracking my entire financial history, building a profile about my earnings, savings, spending habits, etc., giving that information to the government, and selling that information to advertisers, political research and strategy companies, data analyzers, and more.