As a market differentiator, especially in the early stages, free charging is great.
*Availability* of charging was the first concern, however, when I searched for alternatives in places such as Bar Harbor, Maine and Hilton Head (Island), South Carolina.
Once availability was determined, then all things being equal, I'd of course pursue the "free" ones. Now, in general, "free" isn't free. For example, on Hilton Head, there was a free L2 at a... Wendy's iirc. Brand new, 30A service, worked fine - but as we know, 30A (24A) is slow as molasses, and time on pretty much any island is money from an enjoyment perspective). On the other hand, there were 2, count 'em, 2 HPWCs at a (Tesla owner's) fine cantina (100A so 80A service) - guess where I spent happy hour more than once? The fact that they flew in their ribs from a fine Ohio establishment (replete with bibs) didn't hurt.
When I book hotels in non-SC-served areas, of course I stay at the L2-enabled properties when possible.
As far as ubiquitously free is concerned, well, here's the thing. In the early days of wifi, it was common for coffee houses to charge and charge healthily. Today, wifi is free to the customer everywhere with rare exception. If one defines everywhere to truly mean everywhere, then I suspect we'll have to wait another 10 years for satellite coverage.
EV charging being free for all? Sure - someday. It's the definition of free that may get some tweaking is all. Consider even roadway-embedded charging (currently piloted in the UK and elsewhere) - a differentiation between *free* and *freely available* may ensue.
Free supercharging will continue to work and will continue to be a differentiator as the costs of solar and batteries drop. Why? Because it ain't free, folks. When you spend $250K for 2 cars and see how much you have left in 5 years or even 3 years, that point will become glaringly apparent.
In the intermediate term, there will be some hurdles (see Model 3 charging). And the exclusionists will continue to make a contrary case, of course. But in the end? Freely available, for sure. Free? Depends upon your definition and perspective, I suppose.