The "graphics and sounds don't matter if u hav gud gamplay" school of thought just seems to be a recent development arising out of the "retro" phenomenon which also manages to completely misrepresent old games.
That school of thought has absolutely nothing to do with "retro" phenomenon and it's in fact rather old as it can be traced back to Championship Manager/Football Manager games (which started back in 1992), and I'm sure you can also trace it back to Chris Crawford and other developers too.
The thing is that some video games simply don't get better with better art. And in fact, most video games have a limit up to which better art makes any difference. But most importantly, here is the thing that most people miss, good gameplay can make up for bad art, but good art can't make up for bad gameplay. So if you had to choose between the two, which one would you choose?
I also understand that some pedants argue that games are holistic and should get better in all areas. While it's nice to see games get better in all areas, I think this is both bad and boring advice. Boring, because this means that derivative works are better than works that
innovated the things these derivative works use. And when you look at what the makers of derivative works do, that is, that they are people who are simply in a better position to employ basic marketing efforts to exploit previously discovered formulas in an effort to make an
ultimate mix, a predictable mix that will please ultimate criticism pedants but mostly those who never played those original video games before, you can realize it's a rather boring advice.
Not saying that video games aren't better if they are communicating better. If this better art communicates things better, great! Not saying that a video game with bad art is better than the same video game with great art. If you are in a position to do it, then by all means do it! Just saying that a video game with bad art that was released
before a similar video game with better art is the one which is better.
But it's also a bad advice; bad because we don't really only care about what makes a video game better, we also care about what makes a progress, and when you compare the holistic approach to the focused, systematic one where you focus on one thing at a time, it's clear that the holistic approach is a bad one.
So, yeah, folks, you don't have to bother with art. At least not before you can show your game has any merit and any success on its own; you know, as a
game. And only
then should you decide to upgrade the graphics i.e. milk the original discovery. And then, some people will adore you and others will be bored by your output, but at least, you did come up with your own formula.