I gather that Roddenberry intended TNG to be a soft reboot, only loosely consistent with TOS and throwing out or updating whatever parts of it he was unsatisfied with. Even then, he felt that TOS was dated by its technology and attitudes and deserved to be modernized. But once he was out of the picture and fans-turned-pros started joining the writing staff, they started bringing in more TOS nods and treating the modern shows as direct, literal sequels to the original.
Generally, the original creator of a franchise wants to keep it moving forward and innovating, but once its fans take over its writing, they're driven more by nostalgia and tie it more strongly to its past. Similar things happened with modern Doctor Who, and with Marvel Comics when childhood fans started writing the books and bringing back original team members who'd long since moved on or resetting heroes to status quos they'd long since outgrown.