I think it's not always a negative, I mean, it definitely is illegal if you would make your own cryptocurrency in a country where it's not legal to do so; however, if you would make them in country that accepts it, then its not illegal per se. Come to consider that ICOs are being introduced everyday, and they basically introduce a new altcoinc which is a form of cryptocurrency as well. They use it as a means to pay transactions in their companies or programs; they also use it as rewards and payments to people who join in their projects. In that sense, it is not illegal to make your own crypto, given that it is allowed.