Agreed, the dog tags really mean very little (actually nothing) with regards to your soldier weapons access, grading etc. All except the special situation where you want to qualify as full fletched Phantom in the Phantom program, where you need to find the final stand dog tags on the maps. But that is also highlighting a bit the issue, as the dog tags as actually also your soldier level illustrate to other players what you have achieved with your soldier on that very same game platform. Reason why dog tags and other stuff is not transferred from your soldier on one platform to a soldier you may also play on another platform. One could also argue, why should that be possible, as it is maybe easier to do precise longrange sniping on the PC platform versus on the PS4 platform, so is it fair that you could gain the Recon dogtags on the PC and bring them with you to the PS4 platform, where you now play with many players that do not have access to the PC platform? In any case, think it is good that this is kept separate and simple. All you gather and rank up on your solder has to be earned on that same platform!
And lets then agree to keep the exceptional discussion separate regarding the Battlefield Veteran Knife and the 3x scope for the Magnum.
I miss also those myself, and will never be able to get them for BF4, but that is just how it is. ;o)