it feels like a sin to say this but I think the TdF found the right formula of just having ~4hr stages everyday that can be raced intensely from the start. it seems like the riders are not afraid to go all out at that length of stage. i still would like at least one epic 6+ hour mountain stage though.
Which mountain stages were that hard form the start? Every one of them had Van Hooijdonck in the peloton after 2 hours of racing basically. Jumbo pace hard for attrition, but they would do that on a 6h day as much as on a 4h day.
It's also not about fear of long distance, it's just that teams don't wanna burn all their domestiques at the same pace, so you use the Luke Rowes and the Nathan van Hooydoncks for 4 hours on a 6 hour stage instead of for 2 hours on a 4 hour stage.
The one big question for me is to what extent Govenou deliberately avoids long mountain stages and to what extent it's basically just "this is good enough", and how quickly their views on route design change. It's not like they won't do 3 HC climbs in a stage when they will go for the dreadfull Galibier-Croix de Fer-Alpe d'Huez designs any time they like. This year they did take a detour to add Longfry before Loze, they could have just gone through the valley. I also wonder to what extent it's just the consequence of what areas wanna host stages. We haven't seen Agnel-Izoard back but we never had a chance to get it back because the Tour basically never goes to Italy.
Overall I have a much bigger problem with the hard stages being only 'bout that MTF designs than the lack of 220km 6 hour mountain stages.