You cannot divide a pie into a larger pie.
70% is still going to the artists, the money is simply being reallocated. The question is, if indie artists are going to get more, who is going to get less? And will your system actually provide more royalties for indie artists?
I would bet that like all communities and systems, 20% of Spotify’s users are responsible for 80% of the streams, and thus 80% of the royalties. I would also wager that this same 20% of highly engaged music lovers are more likely to discover and listen to new indie artists. They also likely listen to a larger number of artists in any given month than casual users.
Judging by the fact that you wrote this article, I find it safe to assume that you care much more about music and Spotify than the average user. Spotify told me that I listened to 49,912 minutes of music in 2014, so I too consider myself a member of this 20% that listens to more music and cares more than the average user.
With your system, people like us, music lovers, will have the same say in the matter as the casual 80%. My $7 will be divided across tens of bands each month as will yours. While someone who just listens to top 10s here and there will send proportionately more money to the most popular 1% of artists. Everyone who just plays one Jay-Z album in July will send Jay-Z $7. The result is that the most well-payed artists like Rihanna and Justin Timberlake will have fans that are, on average, more valuable than fans of indie bands simply because they are already more famous.
This essentially flips the model giving the 80% of casual streamers 80% of the control. You should never structure a community this way. The most passionate users are the ones who should be catered to. They are the 20% that find and listen to new bands.
If a band needs 8.6 million streams, then the sad truth may be that they need 8.6 million streams. This is the trouble with selling a non-essential good, it is harder to make money.