I would just say the people telling you that are almost certainly people who are not in your target market.
Here are a few examples and 2 of the 3 games are selling at $5 or more.
Environmental Station Alpha was rated highly and sold very well.
Environmental Station Alpha
Necrosphere sold very well and is rated very highly not only on Steam but also big game review sites such as Rock, Paper & Shotgun.
Necrosphere
Much more recently Duck Souls was released on Steam and is also rated very highly on Steam, sites YT etc.
Duck Souls
If you think making the graphics higher resolution will make the game play better or you personally want to make the graphics higher resolution then I'd say go for it. There could be benefits such as allowing the player to have a larger view of the area which would have an impact on gameplay and might be a good thing. Or might not.
I'm just saying I wouldn't personally increase the resolution because some people on the Internet said to increase it. People each have things they like and don't like. You could just as easily have other people tell you "this game should be in 3D" simply because they like 3D games.
It's like the RPS reviewer of Necrosphere said... "personally I love the colorful chunky pixels". It all comes down to the person. And there are lots of people who love chunky pixel graphics just as there are lots of people who hate them.
Again obviously completely up to you and there may be real advantages to increasing resolution such as having more screen real estate for stats, larger area visibility and so on. Just saying do it for good reasons such as these not random net comments.
I could see increasing the resolution of your game as far as the screen size is concerned so everything appears smaller and the player can see more of the level because it is a very short field of view. But you wouldn't even need to redraw the images for that. Just increase the resolution and instantly everything is higher res and player can see further ahead, etc. In fact redrawing the images all larger as well would make it so the field of view is still very small.
