8) the d20 DC system for skills (that took away all DM rulings, as everything was codified)
8) Yeah - this was a pretty significant change. Made them use, essentially, the same mechanic as hitting something in combat. It does make the game easier to learn, but WAY too much is made about it not allowing DM rulings. Player who were savvy with the rules were already lawyering the heck out of things if a DM let them. 3e just put more info out there in the players' hands by default.
Besides a few mentions of IP and repetition of similar fantasy tropes, there was essentially no connection between 3rd edition and any other TSR product.
Here are some of the biggest differences that I was hung up on when first learning 3rd edition:
1) tactical movement on a grid
2) attacks of opportunity (for nearly everything)
3) feats
4) class "balance"
5) Challenge Rating
6) 0-level spells, cantrips, and ever-present spells
7) prestige classes
8) the d20 DC system for skills (that took away all DM rulings, as everything was codified)
9) character wealth by level baked into the system
Anyone else realizing this?
Everyone's experience is different, but I've been playing since the early 80s so have experienced all five editions of AD&D (very little BECMI for me). When 2E came out it was a very much needed clean-up and re-organization of 1E, but essentially the same game - with more options and settings. The problem, though, is that while the RPG world in general was advancing with systems like White Wolf's and the Ars Magica came, D&D was stuck with an anachronistic chassis that harkened back to the halcyon days of the 70s. 3E felt like a (very welcome) modernization of the game.
Where I do agree is that some of the fun tonal qualities of early TSR D&D were lost, and this was very much a generational thing. If OD&D was for Boomers and younger Gen-X, most Gen-Xers cut their teeth on AD&D or BECMI. 3E was the first game that felt very much marketed to Millenials, if the older ones born in the 80s. This trend was greatly strengthened with 4E, which sought to draw in the Warcraft crowd.
5E, in a way, felt like a do-over of 3E, but with a simpler system and a tone that felt more like 80s-90s D&D, if with contemporary art. It was largely successful in what it set out to do: not only create a simpler and more accessible system, but a more classic feel. I don't know for sure, but I think it appealed to a lot of tepid OSR folks, if not the diehards. The OSR scene seems a bit more toned down than it was a decade ago. That said, if WotC goes too far in adjusting core tropes to suite some of the current cultural trends, there might be an emergence of something akin to a "New OSR." But we shall see.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.