Actually the alignment of the route isn't high speed fit, otherwise it's shortest route.
It has to be redeveloped thoroughly, being said that it has great potential but BCT NDLS via KOTA has been already sanctioned with a good amount for High speed route in future.
Also the route via Alwar has lots of good cities, but IMHO the more the cities and towns in route, the more it's slow. The reason that no route is as good as Kota route is that it has long distances between major cities, which helps to...
more... maintain the high speed nature of route.