Quasqueton said:
I eventually considered UA an example of an egotistical and close-minded game designer. “Only stuff *I* personally write will be considered officially official, and my first draft is perfect, as is.”
AD&D
was Gary Gygax's baby by design, and his was the sole name on the books' covers. UA in this regard is no different than the PH, DMG, MM, and MM2 -- other authors contributed ideas and material (classes, spells, magic items, monsters, etc.) but Gygax reworked and edited all of it into a (theoretically) seamless whole, listed himself as author, and credited the original contributor with a (presumably non-royalty-generating) "special thanks" credit.
As for the original creators of the UA material, Roger Moore definitely created the non-human deities, and is specifically credited in that section of the book. I believe both the weapon specialization rules and most/all of the new cleric spells were created by Len Lakofka (or at least co-created by Lakofka and Gygax). Some of the new magic items originally come from modules (IIRC) and Rob Kuntz claims to be the originator of at least one of them (the Iron Bands of Bilarro -- Bilarro being an anagram of Robilar, Rob's main PC). There was an article in Dragon presenting stats for a bunch of new weapons for AD&D, and Gygax's own new weapons article (i.e. the new weapons chapter in UA) presents different stats for some of the same weapons and was billed as a "response" to that article.
A lot of the material in UA
is changed from its original appearances in Dragon -- some of the changes are minor, others (like making the cavalier an entirely separate class rather than a fighter sub-class, allowing the barbarian to use magic items as he levels up, etc.) are pretty significant. So, while your perception that "only stuff *I* write will be considered officially official" is pretty much correct (for better or worse), the perception of "and my first draft is perfect, as is" is less so.