I think there is a place in the GT's for a TTT.
The promotion of gear for the bike and equipment manufacturers is good for the industry. The industry largely funds the sport, so it is therefore good for the sport, in general.
For the other sponsors, they get action photos and video of their team with no other teams' sponsors in the image. That is good for the sponsors, who also fun the sport. E.g. good for the sponsors = good for the sport.
For the fans, the TTT is visually stunning and I - for one - enjoy watching the TTT a great deal. Good for the fans - good for the sport.
This year, the short TTT follows a complicated transfer from an island to mainland France. That trip will be unusual for the Tour. Any rider who suffers from seasickness (admittedly an unlikely event) might have a difficult time. A 15 mile effort is almost as good as a rest day when it comes to recovery and/or rehabilitation of the many riders injured in the crashes during the early stages. Good for the riders = good for the sport.
By having a short TTT, the riders with the strongest teams willl gain a time advantage on their rivals while strong GC riders with weaker teams will not lose so much time that their GC hopes are completely dashed (that was an argument against the longer TTT's of past years).
Having the TTT early in a GT helps to reduce the chance that a team has lost many riders due to injury, abandoning, or missing a time cut.
Cycling is a team sport and there is nothing like a TTT to showcase a team working together without any outside influence from other riders.
I think the Tour organizers have done a masterful job planning our the first three stages - with the obvious exception of making sure the team's buses can all fit under the finish-line banner scaffolding. That was more than a little bit embarassing.
I also think they picked the right day for the TTT, an appropriate distance, and a great city to have as a host, given the cycling tradition of Nice.
The first week of several, if not all, of the past decade's Tours have been real yawners at times. Not this year, though. IMO, the TTT is going to be a great addition to the first week and I'm looking forward to watching!