I have no idea why they didn't just give us Scan/Libra. Not only would that be a player induced toggle, but it would also keep inline with the other FF games in the series. They could have made the spells give more information depending on player actions as well.
For example, Scan as the spell, using it in a BR would opens some strategy and tactic opportunities. You'd be able to get elemental weaknesses, HP, or even possible incaps. Want elemantal info? Toss it in after an elemental spell. Incap info? Toss it after a weapon skill. Or make it have to be casted multiple times to get full info for the enemy. It's not any less immersive than having to bring up your browser and going to a wiki which is what the vast majority of everyone does. Casting Libra would allow us to see if monsters aggro and their level range.
Just saying, but the immersion is not really broken for me by seeing the level of an enemy considering I see BIG *** NUMBERS all the time when I decide to poke one with my weapon. The aggro icon did take the fun out of guessing if something was looking to stick it in my pooper but I can live with the 10 secs I lost finding out. The size of the **** icon though, that definitely needed to be adjusted one way or another.