Yeah, because people use python when it doesn't matter and c++ when it does (including implicitly by calling modules that are backed by c implementations).
That is not an option with FHE. You have to go all in.
Yes but with FHE it also depends on the use-case and how valuable the output is and who is processing it and decrypting the final output.
There are plenty of viable schemes like proxy re-encryption, where you operate on a symmetric key and not on a large blob of encrypted data.
Or financial applications where you are operating on a small set of integers, the speed is not an issue and the output is valuable enough to make it worth it.
It only becomes a problem when operating FHE on a large encrypted dataset to extract encrypted information.
The data extracted will need to offset the costs. As long as companies don't care about privacy, this use-case is non-existent so its not a problem that its slow.
For military operations on the other hand, it might be worth the wait to run a long running process
That is not an option with FHE. You have to go all in.