a) This isn't radio. Spotify's user base isn't that large, so 2% isn't as much as it sounds.
b) The more songs you have, the better chance you have of somebody listening to it. So if you have only one song, yeah that might be hard to hit. But if you have 40, it is easier.
c) Big caveat to my calculation: I don't know what Spotify's sliding scale is. For 2% of the user base, the payout may be significantly larger and thus the required number of plays to make a reasonable income smaller.
d) Spotify's revenue comes from ads, so it makes sense to split it up based on how popular a song/group is. If only 0.01% of the user base is listening to your music, you can't expect Spotify to give you a large piece of the ad revenue generated by their service.
The entertainment industry, whether it be music, tv/movies, or sports, is about popularity. If you can't boost your popularity, it just isn't going to work out, regardless of Spotify's business model. That is the reality.