Maybe it's the old capitalist coming out in me, but I think "should" is a strong word. Free access to wi-fi certainly helps me determine where I'll stay, just like free breakfast is...but if a hotel has enough other amenities so that people are willing to pay for it's wi-fi then so be it...although it is easy enough to get free somewhere, I don't value it enough to pay for it.
I agree with you John, that market forces will drive this. But the demand for "free" wifi (understanding there is a cost to this perk) is so huge I think it will be the standard in a few years. Those hotels that don't want to offer it will see a drop in their occupancy. Like you, I pick hotels that offer if at no added charge. I also like to look for free parking and free breakfast. "Free" is so tempting, isn't it? But I dislike unbundling of charges in all forms. Set a price that includes everything a room usually comes with and then let people decide what they want.