for tags yes, there are some more popular than others, but too popular is also not good.. let's say there are 100k horror games, those looking for horror will only see the ones that are best selling or popular, except for a few days in which you are in the newcomers,
so you need to go more specific, for alice's game it might be something like "female lead platformer" or "cartoon style platformer" etc, you need to try to be very specific by using the tags that describe the game as well as using the generic tags, think about the people who are looking for and the elements that your game has, then put them in the tags..
however for the tags they are important yes, but I don't think so much as one can expect, there are still a lot of games of the same genre out there.. but it's ok to put a lot of them both specific and generic :)
3d is perceived as something more professional especially when it is photorealistic which requires a lot of work, it is true that on the technical side it is much more difficult to manage, but it is also true that doing 2d on the artistic side is not something easy :)