Or they are representations of different facets of ideology and the human condition, and some folks like to explore those ideas.
I get attracted to exotic races for similar reasons. Many exotic races live in communities and have ideals that are quite different from the "normal" human, and this can be interesting when you want to try and play a character like that in a campaign, your character may have a very different outlook in a certain situation than the rest of their party members.
Look at the Githyanki or the Yuan-ti, their familial practices are very different from humans, and they have very different attitudes towards relationships and intimacy, distinctly non-human attitudes. This could come up in a game and create an interesting juxtaposition in your party. The issue of fantasy prejudice against traditionally "evil" races is also a thing that groups may or may not get into (depends on the group and the campaign).
This may not be a thing for some exotic races, but it is for some of them. I personally love the planetouched races, even though most people consider them to be just humans with extra bits. My longest running characters in actual table games have been an Aasimar and an Air Genasi, and I have had great fun playing them, and unless your the type of person that leads every damn conversation with "I am Xcharacternamex and I am EXOTIC! Look at how UNUSUAL and STRANGE I am!" their otherness really doesn't come up as often as people think it might (although this may change by campaign).
Exactly this!
Jeremy Crawford gave an interesting interview on their thought process that went into Tashas Cauldron of Everything, and why they wanted to make the rules for various races a lot more flexible and accessible for players. I'll look around for it later and post it if I find it.
And ultimately everyone wants something different out of these kinds of games. Sword and board, lots of Puzzles, high fantasy RP, etc.
The thing is that the more races they added, the more diluted and more work they have to put into the dialogue options, time is a limited resource, and it's at the point whether they want to focus on the gameplay aspect, expanding more story, or adding races. No, they can't do all of them. It is just not possible as time and development cost will add up, and the opportunity cost will be taken from another aspect. There are a lot of interesting races, and yes, they will be adding more in the final game. With monster races, it would especially more difficult to add without completely different reactions. If they do it just for cosmetic purpose and NPCs just react to them the same way then there is really no point. The monster race would just be skin instead of bearing any significance. I would rather for them to focus on the races they have and do it well. While people appreciate the freedom and customization in Western games, most players play the game very generically, Larian already said that most people play as a boring humans and a major majority sided with the good faction. It's not just in this game, but many other games from what I have read. With that being said, I do like variety in these games, so even only a minority of people use these options to play as other races or being evil, it's still nice for replay value and freedom. With that being said, they should focus on providing a complete experience for the game and building up the contents for the existence races and the additional races they plan to add instead of trying to add as much things as possible while neglecting other aspects. Monster races like goblin would be one of the things that may be best to leave out at least for the launch version.
I think this is a totally fair and well reasoned point, but I think Ayvahs response hits it on the nose as for why I pop into forums in support of various monster races. If enough people are asking for specific races, it becomes worth the time and effort it takes to add them. Ultimately we know that at this point in the game development they are planning on adding more races, we just don't know which ones. So now, as they are doing the work, it would be the time to let Larian know which ones we'd like to see.
Regardless of which ones they are adding I'd be very interested in seeing if they have any stats on how many people are asking for which races.
