Thanks for the mention of Steemia :D
We do take beneficiare because we pay servers and there is not way at the moment for us to pay it on our own. However, just 10% (or less depending on the bill) will be used to cover the development of the application while the rest will be used to power up our bot voting account to give back to the community what we take.
Our goal is not to growth alone. We want to growth with you!
What I've noticed is that there are lot of users that don't know about beneficiares. We wanted to be transparent and stated this in the introduction post unlikely another projects. Some of the projects over the blockchain do take 10%, 15%, 20%, and 25%. Even, there are some that also take beneficiary from comments (which I feel it is like an abuse).
Most of the users that asked me about this percentage and how this will be charged, they didn't know that those apps they use actually takes beneficiare.
I don't mind beneficiary rewards because I know they pay for development.