It could be a tad confusing for people who have collectible items like physical coins. When people are transferring private keys, they'll have to clarify whether the coins were sent there before the forks or after them.
Calculating the value could get harder if there are a lot more forks with drastically lower prices and volume (like all of the bullshit ones that have been suggested recently).
I wouldn't call it the "value of Bitcoin" though, since the value of BTC itself is still the same.
Unfortunately, it is "the value of Bitcoin."
We have to define that by the value of a Bitcoin private key.
Bitcoin private keys now are of two types, those which have not had the split values retrieved, and those which have splittable values resident.
It is what it is.