There's an interesting parallel between Lucas and Roddenberry.
Both were "typecast" as "Mr. STAR WARS" and "Mr. STAR TREK".
Both receive most of the credit for being the genius visionaries behind their respective franchises.
Both were/are lousy writers. Of the few TREK episodes Roddenberry actually wrote, only the original pilot was an out-of-the-ballpark-good script. His other scripts ranged from so-so ("Mudd's Women") to utterly lousy ("The Omega Glory", "Turnabout Intruder").
The original SW trilogy was very collaborative, with the first film, in particular, being saved in post-production by editing and window-dressing (music, FX, etc.). EMPIRE's creative success was largely due to Kernsher and Kasdan.
And Roddenberry, being a notorious credit-stealer, was more of a guiding influence than anything else. Gene Coon was perhaps the person most responsible for the feel of TOS as we know it, having served as producer after the first dozen or so episodes, penning many great episodes, and rewriting others.
Both Roddenberry and Lucas later came back to their respective franchises, with mixed results.
Lucas made the prequels, without a system of checks and balances.
Roddenberry came to believe the hype being repeated to him over and over again by fandom, with the result that STAR TREK-THE MOTION PICTURE depicted a boring, bland, "perfect" future--which was not at all what TOS was about.
The critical failure of that film led to his removal as creative controller, and it took two outsiders (Harve Bennett and Nick Meyer) to get back to the heart of TOS with THE WRATH OF KHAN.
And then Roddenberry went off and created TNG, which, at first, was in the vein of ST-TMP: bland, with no conflicts between the main characters. That first season is just horrible.
Both Lucas and Roddenberry, after being hailed as visionaries, decided that their franchises needed to be IMPORTANT, to the detriment of said franchises.
STAR WARS went from the ultimate popcorn movie to a "deep", mythic, multipart "Saga", which resulted in the 6-film patchwork quilt we know today. The original film is the only one that doesn't fit within that framework.
STAR TREK went from a fun action-adventure-drama series to a talky, bland, preachy series about how perfect man will be in the future. The original series is the only one that doesn't fit within the framework of the spin-offs. And ENTERPRISE went out of its way to erase TOS and steal many of that show's "firsts" (by showing an Enterprise before Kirk's, having first contact with many races that were originally first contacted in TOS, etc.).
Far and away, for me, TOS (third season aside) and the original SW film are the best incarnations of those franchises. Almost everything that has come after has served to undermine and/or erase/supplant those original, iconic versions.
Talk about biting the hand that feeds!