I took the fated Trenhotel Joan Miró that the author talks about. It was a little over 100€ and covered the distance in twelve hours, like the author said. After getting off that train, economically I could not fathom why anybody would ever subject themselves to that experience again.
The 100€ got me a seat in the back of the train in a semi-reclined seat (the least expensive ticket I could buy). I booked it about four weeks in advance. For 150€, I could get an actual bed to sleep in (four to a compartment), and the price/service level went up from there. If the train had free food or even just free water, Wi-Fi, showers, and such like you describe (at least at that price level), it'd potentially be a different experience. But Trenhotel's stock is about as old as it gets, and what you get for the base price of 100€ makes for quite an unfortunate twelve hours.
I just went to Vueling, and I can fly from Barcelona to Paris for 40€ in two hours. Even with security, time to/from the airport and such, I'm still saving time and money. Copious amounts of baggage is the only thing left out, but I could pay 100€ to check piles and piles of bags, and now I spend slightly more than the Trenhotel and arrive five times faster.
High speed trains make sense for semi-long distances. Paris to Amsterdam is a great example. Three hours on modern equipment is very doable, and a plane ride can't beat that in time (fixed costs of security and required early arrival are too high). Comfort is superior, and the price will come down. The author makes the point that the cost is 2x but the travel time is only slightly faster. These routes were just inaugurated, and the stock is fresh out of the factory. Give it a few years, and they will come down. I'll bet you the old "vintage" routes that the author pines over were pretty darn expensive when they too were first inaugurated.
For the <4 hour trips, high speed rail is excellent, and I believe those prices will fall. But anything longer than that, forget the night trains. They're only semi-useful for tourists and backpackers, and I'm shocked they still operate. I'll fly, thanks.