buying a Tesla with supercharger access gives me the security that IF I want to make a longer trip, I will have access to a easy to use really fast charging network almost everywhere I can think I will ever want to drive in Europe. That the it is "free" is a plus, but not essential.
Like I said, it's nice to have if you planned on taking a longer trip.. But I don't think its as much a selling point as a lot of people make it out to be. For the most part I think EVs are still second cars for most people. Its hard to argue either way anyways until the cost is known. Is $2,000-3,000 extra for supercharger access worth it if you only take 1-2 longer trips a year?
When the model 3 configurator eventually launches, I'll probably not pay the extra for supercharger access, especially if its just a software unlock that I can access at anytime.