Also after paying the 'remove ads' price, which will likely be cheaper than the price I'm planning to sell it for on Steam (thinking $2.99 for mobile right now), the game will effectively become the same as the Steam version anyway.

I agree that it sucks. I wish I could just put $2.99 as the price and it would still have a chance of selling decently. One of the iOS games I made a long time ago I did exactly that (actually I priced it at $1.99). But people were also willing to pay $1-2 for Angry Bird-style mobile games by the millions back then.

Now there are so many free games on there, they seem to just skip over to the next free game instead, and maybe pay to have ads removed (my own partner does this, bounce from free game to free game, and if she likes the game she pays to remove the ads).