As you have said people are using it for storing values but wasn't it suppose to help people to use it as an alternative to fiat? If people buy it only to hold it as they did with gold and other precious commodities then we can not consider it as a payments system. It become an ultimate way of storing values which redirected its sole purpose of creation.
What Bitcoin is for is totally up to you. You're not forced to use it as a currency if you don't want to; because freedom is one of the main points, right? Satoshi put up the groundwork on the whitepaper, but in the end it will be totally up to the people what the direction of Bitcoin will go, not Satoshi.