IMHO there's no good reason for it not to be used in TvZ. I see vessels being picked off left and right after getting plagued, or needing to be brought back to be repaired.
The APM argument makes zero sense because it takes more APM to bring your damaged vessels back to be repaired, whereas there are so many benefits to getting restoration (You could bait plagues out so the M&M army doesn't get plagued, you could use restoration on plagued BCs, etc)
Thoughts? Has anyone asked a progamer about why they don't research it?