To put it bluntly and I mean no offense whatsoever - you come across as completely nuts trying to charge 10 EUR for a damn color scheme. That's basically what 200K people think when dismissing your nag.
The fact that 200k people have downloaded it means it has value.
I'm actually more surprised 200k people have downloaded a custom colour scheme. But since they have, I don't think 10 EUR is excessive to charge for something like that.
Rationally it makes some sense, but irrationally - charging money for such triviality as a choice of colors is ridiculous.
I can see buying _icons_ being a bit more justified, because it implies at least some amount of non-trivial work on your end, but I don't really know anyone willing to pay for better code editor icons.
Also the fact that you offering to buy a "license" is off-putting, again considering the context of selling a set of RGB values. It's too grandiose, which too contributes to this looking nuts. Just say "buy" the scheme and it'll already be much better.
I understand charging for a code editor theme is not common practice. However, I don't see much difference between the work that goes into designing and developing a simple (Wordpress) web theme and a code editor theme. In the end a web theme is also a set of RGB values and other styling settings. And charging for that is acceptable.
I think it depends on what you think is trivial and what is not. I think designing a coherent theme is not trivial.
I'm actually more surprised 200k people have downloaded a custom colour scheme. But since they have, I don't think 10 EUR is excessive to charge for something like that.