Inara does nothing bur mirror FDev data for the game. When people say it should be in game they don't mean take it. They mean put all it's features into the game properly which FDev is 100% entitled to do with their own data. They can but will not fix their own UI and data search capabilities and have them work realtime from real data not uploads.
No, Inara collects and collates the data and puts it into a usable format, they aren't mirroring FDEV data, FDEV have stated in the past that the databases they use aren't set up to easily extract the the data players want in the way players want it, it would a huge burden to do that. The idea here for Inara was to take that data and put it into a database and format that was useful for players, and that's the bit you would be stealing. People invest years lives into these things, and you want FDEV to casually take it away and make Inara and the entire process pointless and a waste of time? What about Spansh and ED Astrometrics, you want to take them as well?
Now to point out, the reason the data has never been available directly from FDEV is because they don't want to just supply everything to the player, the idea from the very beginning was to allow players to explore and gather data themselves and analyse it, from the very beginning it was intended to be a player driven activity with little input from FDEV, that activity has kept players invested the game for many years, they aren't going to change that now, and by all accounts it would be a major change to their systems to even do so.