10 percent POS rate isn't to bad, there are so many other coins out there that are like 100%  or 1000%, do people really think that those coins wont flood the market with that many.
10 percent is reasonable any higher and you have a problem. If it reduces every year then you have an even better control over the price too. I personally think over time it should get towards 2% or 1 percent so that the POS mechanism still works.