Everyone is arguing from the same direction, from the POV of the consumer. I'm going to take the argument from the opposite direction, the POV of the artist, because I'd be interested to see what the responses to that would be in contrast to the responses already aired. Note: I'm not an artist or creator, I'm just interested in debating this from a different angle to see what it brings up.
The artist, or content creator, should be able to make any statement they wish without being censored. Most would agree with this so let's go a step further: The artist should be able to reserve the right to have any content warnings removed from their work for any reason. Some works of art/books/films/games are supposed to be confrontational, disturbing, controversial, thought-provoking, difficult, unpleasant, disrespectful, challenging - all that lovely stuff.
Everyone that makes these things has the right to express themselves without their work being pre-emptively diluted (or "spoiled") by warnings indicating the type and/or severity of the content contained within. Sometimes this is achieved by being unexpectedly shocking, other times the theme of the work itself requires it to get up in peoples faces that wouldn't normally choose to expose themselves to it, say if their aim is to present an unpopular political point or try to change or challenge society or attitudes in some way. They might even just want to piss people off! And that's fine, no-one has an intrinsic right to not be offended. Perhaps the only point someone making this argument could reasonably be expected to concede is let's keep the "not suitable for young children" warnings in the obvious cases - but that's it.
Obviously I'm devil's advocating here; my actual opinion falls into a more central position. I believe no-one should be censored and should have the right to make anything they wish saying anything they want it to say in whatever manner they deem conveys the message most effectively. I also believe that empathy is a really cool thing and more humans should practise it in order to be decent and kind to one another so the world can be better. These two statements don't have to be mutually exclusive, but in certain situations they butt heads and one or the other has to give (Je suis Charlie debacle, anyone?)
For the record, anyone suggesting any kind of government regulation on what content should or shouldn't be allowed to be portrayed in works of fiction I think is super-wrong. On the flipside, people don't have the right to protection from the consequences of the shitty things they say or create, so if they make pariahs of themselves and get shunned and boycotted because of whatever offensive thing they made, that's on them.