Yeah, i get that it is because people want riders to be more rounded to win a Grand Tour. But in my opinion if you look at the list of recent GT winners they are almost always quite well-rounded riders capable of riding good ITTs, Climbing well and having a good punch.
Personally I think that it is much harder to make significant time gaps on mountain stages (especially because those are not individually raced) than it is to make significant time gaps on a TT. So even with the decreasing amount of TT kilometres, the well rounded riders still have a very significant advantage over the less rounded riders. In my opinion increasing the number of TT kilomtres would even decrease the chances of the best rounded rider winning the GT, because the advantage for a Great TT-er and reasonable climber would become too big over a reasonable TT-er and Great Climber.
Maybe but that is mainly for me down to Pogacar and Roglic actually being better climbers than 'pure' climbers like Landa. This means that they are already ahead rather than making up for their climbing level with all the other aspects of their skillset.