If your one of those people, and there are many of them, that only want one rifle, well the 06 may be the choice for you. There are others that I would choose, the 6.5x55 for instance, will do most every thing the 06 will do, and some things it wont, and less recoil.
There are many many other choices out there that are as capable or more so than the 06 for a single rifle owner.
For those of us that choose to have more than one rifle, there is no reason to have a 06 in the cabinet, as every thing it does, another caliber will do the same in spades.
It is not that the 06 is not capable. It is that there are many more modern calibers that are much more capable.