The charging does add half an hour to a three-and-a-half hour trip, about 15%; maybe a little longer if it's below freezing. That's the price you pay to be off gasoline before it was cool, you know that up front.
But look at the distances: The long leg is only 144 miles, well within Model S range. And Musk has acknowledged that on the east coast, in cold weather, those charging stations should be closer together, which could bring that trip closer to 100 miles per leg, which presumably can be done in comfort even in the cold.
It's totally doable; takes a little longer, but I like to stretch my legs and grab a cheeseburger during that drive anyway. That just doesn't say "niche" to me. The people who are making that trip every day are the niche.