your opinion is not the only possible opinion. I used the hsl to paris once. it was amazing. In three hours i was home and could go on with my life. a plane would not have been faster. paris is a little bit too far to commute these days but one would imagine people will use it to commute to brussels. that's also the real weakness of sleeper trains: they are only useful for tourists. whereas most trains are being used for home-work commute.