The current reality is that publishers are looking for manuscripts that are pretty much ready to go to press. The days of an editor laboriously working their way through a manuscript with the author have long gone. Yes, an amazing story or a stunning idea will make it through regardless of the quality of the presentation, but that's going to be true for only the most fabulous of tales. If an editor has a choice between two manuscripts of roughly equal story quality they'll choose the one which requires least work.
And people do care. The most common complaint about self published work is the quality of the editing. People don't like reading work with poor punctuation, spelling, grammar etc and they can, and do, complain. It doesn't matter how wonderful the story telling is if no one gets beyond the first few pages.
I think it's like dressing up to go to some amazing party. You've dressed incredibly carefully in your best clothes, then just before leaving you nip to the loo and set off with your skirt tucked up in your knickers/flies undone and shirt sticking out.
Finally, what does poorly presented work say about your attitude? It's easy enough to employ a copy editor, although the more mistakes there are, the more expensive it is. With luck you can find a friend who'll do it for you for free/alcohol/favours.
Either way, you have to try to make your work as perfect as possible. If you can't be bothered to make sure your work is the best it can be, then why should anyone else be bothered?