I can kind of understand the sentiment but I'm sorry, who are you to say quit the personal branding. The average career for a first grader lasts 43 games. Players have every right to hype themselves up in order to secure brand deals and better contracts, and honestly good on them for doing it.
You're are right when you say that 20 years ago nobody cared what you or anyone else did, but that doesn't mean you didn't have any self interest or ego. Remember Michael Jordan? I am sure you do! Well, guess what he was doing 20 years ago? Living off his own personal brand. You know 30 years ago the "Be like Mike" Gatorade advertisement aired as well. It's weird you have turned this into some sort of generational thing when this was even more commonplace in your generation, minus the social media.