It most certainly remove or diminish the consequences. PG-13: Person gets shot, he falls over, there is no hint of damage, there isn't a "Oh **** he's dead" moment, he's just some dude and maybe he will get up later or something.
You want your audience to go "Woah that's a bit much" which forces them to acknowledge the consequence of what has happened. It makes the you consider maybe there were some other solution to the conflict. There is a scene in the first movie where Togusa complains about the method used and the mess they made, mirroring the audience's reaction.
The tank scene didn't need blood at that point in time, they selectively excluded it. In this case blood would have detracted from showing how much of a robot she is. It also made the following scene more shocking as ultra violence shown throughout the movie as being absolutely "You are not coming back from this" level.
I am guessing your threshold for viewing fictional violence is much lower than mine. I am more willing to see it being used to it's full effect rather than shy away.
Violence is another tool to use for story telling. It is no more lazy than any other tool and open to misuse like everything else. Reducing the level of violence wouldn't be true to the source material anyway and was absolutely pivotal for a movie like Dredd. Just maybe this isn't a movie for you.
Looking at the trailer I think there will be an R as they are showing blood sprays even though they are white. They show Aramaki straight up finishes a guy off and the actor who plays him is famously in really violent movies. The Matrix got rated R and if the level of violence seen in the trailer holds up it would be an R. If they re going to get an R anyway you might as well use it to full effect. The rating board doesn't look kindly to lesbians so that is another R flag.
Besides, the R market is really under-served for quite a while only to be punctuated with films like District 9, Deadpool, John Wick, Hardcore Henry, Kingsmen and Dredd. There just aren't that many films of that type. Is this a movie that should not be PG-13.
PG-13 is an albatross that needs to be done away with. It makes cartoons out of violence and other mature content. It induces a self censorship effect. I ruins films that should have went for a higher rating.