It would be reasonable for the Player and GM to have some conversation about what monsters are likely to be common in the game world.
Why? Players don't design the game world.
------------------------------------
I think many people may be overlooking something here with regards to this "communication" trek they are on.
"Why" in response to "i don't like it" isn't the first question, but at least the second.
Let's look at a whole conversation:
DM: I don't like it
Player: Why?
But how did we get here? There had to be at least one question before. The one to which "I don't like it" was the answer to. So I see it progressing more like this which actually puts this "why" looking for more information to be a 3rd question in a line of question:
Player: Can I have X?
DM: No.
Player: Why?
DM: I don't like it.
Player: Why?
Doesn't look very much like communication to me, already looking very close to badgering the DM at this point.
I also don't think it possible if the conversation went something like this:
DM: In this world there will be dragonborn and goblins, but no kobolds, <interrupted>
Player: Why?
That already shows signs the player would be disruptive for not waiting until the end of the description where they might have found out more had they kept there questions to the end.
"I don't like it", was already an attempt to qualify the reason the player wasn't allowed to use X.
I don't play 20 questions, I play D&D. Those that want to play 20 questions may do so, but trying to quantify that for all, is not within their rights.
There is way too much stuff to get done to allow too many questions form players if you intend to play a game. "Can I have/use...", is always allowed, and asking for a reason why not after that is sometimes allowed, but once you have ben given a reason by the DM, anything after that is badgering. To me that means this player will be problematic and disruptive during the game.
Different people have different levels on how far they can be "pushed". A fair and honest answer given is more than enough.
Take into account this player is trying all sorts of things some the reason being "I don't like it", some being things that will be found out later, some being this "communication". Let us say this player has tried to ask if they can have 10 different things. All are little things, but things not allowed. Now not only has that player wasted an hour of the DMs time ,but the DM too has wasted an hour of everyone else's game time for this one player.
So all this "communication" stuff is way off track of the topic.
Why is "I don't like it" not good enough?
Simply put, it is good enough. But some will not accept it at all.