I can give some insight as to why I think they went this was, and why I think it was a good decision.
1) the obvious one was to make the setting different, like the steel currency and kender. Dragonlance was the first setting to deviate from core rules, and so the changes were tentative, and orcs didn't really matter. By the time Dark Sun came round, nine years later, the writers where much bolder. If you look at the Baldur's Gate computer game, there were no orcs in it. Bioware where explicit that they were bored with ubiquitous orcs and wanted to use some of the less frequently used generic monstrous humanoids (xvarts, hobgoblins and gnolls).
2) From an authorial point of view, you only include a story element if you intend to do something with it. And Dragonlance was always highly focused on a single story. Orcs basically have two stories you can tell with them. Either they are the minions of evil, or you subvert the minions of evil story, and they are misunderstood noble warriors. Since the Dragonlance story is focused on dragons, it needed dragon-related minions of evil so that slot was taken, and since Dragonlance was focused on black and white obvious morality, it had no place for a subversive "evil isn't really evil" story.
3) With hindsight, this happened to be fortuitous, since the much less human looking draconians avoid the unfortunate racist connotations that orcs carry these days.
3b) Also, draconians, with their special abilities, make much more interesting combat opponents.
1) And, as we've seen through time, there are much better ways of differentiating settings than banning core aspects of the game from them. Orcs don't need to be banned for Dragonlance to be different from the Forgotten Realms.
2) That's from an authorial point of view. Not from a worldbuilding one. Dragonlance is a setting. Sure, the main storyline, War of the Lance, is what most people know it for, but the world should be designed as a TTRPG setting. Not as a novel setting. Also, the "they didn't want orcs because Draconians are the world's always evil monsters" argument doesn't work because the setting still has Goblinoids. If they were truly aiming for "Draconians are this setting's always-evil monsters so we don't need others", they wouldn't have included the Goblinoids.
3) You're right. But "Orcs are problematic" is also a part of other worlds and Dragonlance has more than its fair share of things that didn't age well.
4) Sure. But if they're not always-evil monsters, they don't need to be fun in combat.
There is no "over the newer community". You're making a purposefully ugly and divisive comment when I and others here are not doing that. But it seems by painting certain fans of settings as bad (for the game) is your ultimate goal otherwise why characterise them as such.
Notice your language and notice mine.
There is a newer community of D&D players that were brought in through 5e. They have different views of what the game is and should be than many of the players that have been around since Dragonlance was originally published. And newer players are less likely to be "setting purists" for Dragonlance, because they probably don't know much about the setting.
There is no reason a re-released setting cannot remain true to what has come before, and be presented in a digestible format that new players can grok.
There is no either/or here. Now if you didn't like the original setting to begin with - just say you don't like it. Changing it around so much that it is just a skinsuit trading on nostalgia, and not expecting older fans to point it out is a bit weak sauce.
Like I said earlier, the amount of older lore that actually did need to change is, and was, much, much smaller than the wholesale lore changes WotC ultimately did make.
We haven't seen most of the changes yet. "The wholesale lore changes WotC ultimately did make" are currently unknown. We know that the Mages of High Sorcery have changed a bit to fit 5e's version of arcane spellcasters, and we have art that shows the Knights of Solamnia without their signature mustaches, but otherwise we currently do not know what changes WotC have made to the setting.
I have mixed feelings about Dragonlance. There is a lot of it that I think is really bad (Tinker Gnomes, Kender, Gully Dwarves, how it deals with Alignment, time-travel, the backstory of Draconians, etc), but there are parts that I really, really like. Dragon-riding knights, seafaring minotaurs, Lord Soth, flying citadels, wizards binding themselves to one of the moons (even though I think it's dumb that they tell everyone their alignment through their robes), and a lot more. There is a big chunk of the setting that I dump in the garbage, lots of parts that I would recycle into new/revised ideas, and a lot that I would keep the same and/or expand upon.
