"I am, however, uncertain what effect 2D graphics have in terms of interest and sales of games. What is your experience as a game developer or gamer? Do you have any data/statistics to share on this?"
I don't know if something like that exists... blockbusters triple As usually spend millions with the game and with marketing, and even though they can easlly flop due to the overall quality (Marvel Avengers and Fast and Furious as current examples, but we can get examples for everything of course)
It depends much more with how much you'll spend with marketing... in the end, everything has its public (and after the marketing, people will judge its overall quality).
We usually try to make games we always wanted to play or an idea we think that would be great... but on all cases, we first do a game for ourselves with the style that most draws our attention, because if it is for you, you, at least, can assure its quality (So, how do you truly idealize this game? You first do think of it being in 3D?)... later, the people that have your same taste will get to your game and will turn into your public (with marketing too, of course, people have to know it exists).
2D games have the advantages of being easier to do for a single person or a small group and of running on every hardware possible... those games usually are the salvation of people with modest hardware that still want to play nowadays games.