I'm curious about all this because I just don't understand the thought process.
See, I started with B/ED&D. Played/DMed for a year or so, then found AD&D1. AD&D1 had more options and more detail. We switched over to Advanced.
I DMed with the PHB, DMG, MM, and FF. Later I added MM2. UA was given to me, but I never really used anything from it. [I think one guy tried a cavalier, once.] I never bought or used DSG, WSG, etc. The Players just used the PHB.
Years later, when AD&D2 was released, I looked through the books. My statment at the time was, "They changed things that were fine, and they didn't change things that needed fixing." So I continued to DM AD&D1.
I ran a series of campaigns for about 15 years in AD&D1 without ever being concerned with what TSR was putting out during that time. I saw the DSG and WSG, AD&D2, and some of the supplemental books, but their publication didn't affect me at all with regard to my game. TSR could have put out crap on a stick and it wouldn't have affected *my* campaign. After the original core books (and the monster books), I didn't need "support" products for my game. If TSR had completely gone out of business, my game would not have suffered. So I just don't understand the concept of leaving a core game system because supplemental/optional/secondary/irrelevant products being bad.
When I quit D&D, it was because I quit RPGing.
Quasqueton