Half Orcs made their return in Monstrous Compendium Vol. 1 published in 1989. That was further expanded out in The Complete Book of Humanoids (1993). There was also Player's Options - Skills & Powers (1995).
Assassins were turned into <and so on>
Let me guess you actually never played AD&D 2E or you haven't played it in a very long time and your memory has failed you due to old age.
I played AD&D 2e through most of the 1990s; it was the edition I
mostly grew up with. I did, however, have access early on to some 1e materials, and that came as an early warning that there was better, more interesting material out there. When I make the claim that the modules and supplements were generally shit, or that the core rules were decent but a decline from 1e, I am speaking from experience. Finding the 1e/Basic-Expert classics a few years later was a revelation: here was a much better D&D than what I had known!
Some of the removed content was later made available in supplements. That's a red herring. Most people play core with only a handful of extra books (some OK, some horribly designed - Complete Book of Elves and Psionics, anyone?), not to mention this means paying for "DLC" that used to be part of the core rules. That does not undo the bowdlerisation of the core rulebooks, which are slightly cleaned up and better organised, but lack the wealth of material and insight found in the 1e lineup. The 2e DMG, in particular, is entirely useless in learning how to set up a campaign, write an adventure, or actually run the game. This, once again, is painful personal experience. (What I learned, I did from example.)
Oh boy what good modules that came out is your idiotic question? I guess Pool of Radiance, Curse of the Azure Bonds, etc... don't count. What about the the adventures for Dragonlance? Most of the iconic adventures are from the OD&D and AD&D 1E/2E era. Then you had to contend with the adaptations of those modules to SSI's Gold Box games that used a modified AD&D 2E ruleset.
As for the writer's guide, this was standard for print, radio, tv, and movies. I'll take this writer's guide over the current trash being pushed that is for the destruction of all things moral and good to pursue pleasure at all costs.
Curse of the Azure Bonds and Pool of Radiance are computer games, and good at that. The print versions are adaptations (sadly, fairly slavish ones). At least they eschew the storyfaggotry and blatant railroading that became standard with the execrable Dragonlance module series - rightfully and almost universally considered
the main harbringers of decline in old-school gaming. Turns out replicating medicre chick lit on the tabletop does not make for any sort of excellence.
There are good supplements from the late 1e and 2e era, mainly the campaign settings in their first versions. However, TSR severely neglected the general AD&D line, flooding it with badly made shovelware that saw no playtesting (since the talented Lorraine Williams forbid playtesting during work hours), and was often released in a barely coherent fashion because Random House had a contract to buy enormous quantities of TSR product sight unseen, and TSR tended to be short on cash. Writing staff at the time mainly consisted of failed novellists who saw game writing as a jumping board to the more lucrative novel division. The results were predictable:
it was a model which only produced quality accidentally, and when it did so, it soon buried it in mounds of shit. Exhibit number one: the initial Dark Sun line, and what followed.