Well, the very idea of "Roddenberry purism" is kind of unrealistic, because Roddenberry wasn't a purist about his own work; he never hesitated to reinvent and retcon it when he had a better idea later on. As I've said before, creators and fans see a work differently. Fans see only the end product, so to them a work is a fixed and monolithic thing. But the creator of the work takes it through many drafts and revisions, goes through many ideas that are refined or completely abandoned along the way, and thus sees the work as the end result of a process of change and refinement. And often the endpoint isn't one the creator chose, but rather one the creator was forced to settle for by scheduling or logistical necessity. So creators are rarely as attached to the final form of their creations as the fans can be, and often welcome the opportunity to go back and correct mistakes, flesh out details, and rework things they've reconsidered.
And we know Roddenberry did this a number of times with Trek. The "laser" thing from "The Cage" was one of the first mistakes he regretted and corrected. He recognized, after the pilot had been made, that even though lasers had only existed for a few years, people already knew their abilities well enough to know that they couldn't do the things they were shown to do in the pilot. So he abandoned the "laser" terminology and replaced it with "phaser." He was forced to keep the two uses of "laser" in the "Cage" footage he recycled into "The Menagerie" because it would've been prohibitive to get Jeffrey Hunter and Peter Duryea back to redub their dialogue, but otherwise he just abandoned it altogether. When TMP came along, with more money and better technology for FX makeup, he had the Klingons redesigned and asked fans to accept that they'd always looked that way. In the preface to his TMP novelization, he pretended that he was a 23rd-century producer and that TOS had been a dramatization of Kirk's "real" adventures, and admitted that his version had been unrealistic and exaggerated, taking some liberties with the facts. And by the time TNG came along, he considered much of TOS to be apocryphal and was willing to ignore or retcon a lot of it, wanting TNG to be the new, revised canonical version of the universe.
So Roddenberry wasn't a purist about Trek because Trek was never a pure representation of what he wanted. Like any television series, it was the result of a lot of collaboration, compromise, approximation, error, and desperation. And like any creator, he changed his mind over the years about a lot of the things he had originally wanted or liked.
And of course Roddenberry's view of himself -- or at least the way he presented himself -- evolved as well. In the '60s, he didn't consider himself a philosopher or a visionary. He was a TV producer and he was trying to make a buck. Sure, he had some things to say, some innovative approaches to doing SF on TV, but his motivations were pragmatic. It was only later that he got caught up in fandom's embrace of ST's philosophy and bought into the image of himself as a visionary. People today tend to base their image of the man on that version of him, but it doesn't really fit who he was and what he wanted when he made TOS. So there's no "pure" version of who Roddenberry was as a producer any more than there's a single pure version of his creative vision.