Good grief. Trek had lazy writers throughout its history. This is an absurd idea that TOS/TNG/ETC did diversity differently. It didn't as much as our memories tell us it did.I think what the veteran fans don't like is bad television, and that's what they've been treated to. It's the fault of lazy writers. TOS/TNG/DS9 whatever, they presented diversity as something that was so acceptable in the future that the characters rarely if ever had to say something about it. Yes, there were a few shows here and there, but for the most part, they didn't wear it on their uniforms like the "modern" shows do. I don't have a problem with it, but when older folk complain about them, and I hear why, that's what I immediately think about. They're just not very good writers and they revert to lazy troupes and writing styles.
That's why I say new Trek is average. Just like all other series before it.