^I just don't see how that's fundamentally different from before.
In volume, for one.
From TNG premier till the end of ENT we had 20-50 televised episodes per year, plus 20ish novels.
Now we have about 12 novels a year.
It's of course true that Star Trek has always dealt with conflict, political turmoil, torture, terrorism and peril on the galactic scale, but for 5 of those stories one also had 50 other stories that dealt with more localized and lighter matters. So naturally the overall feel is perceived to be darker in recent years.