darjr
I crit!
I get your point, funny though I didn't see it that way, though I have explained rolling to cast as a simplification without saving throws or to hit rolls.Under Terrain on page 89.
“Attacking or casting a spell on a creature that is hiding at least half its body behind interposing terrain has disadvantage. If you can't see a creature at all due to terrain, you can't target it.”
You lose a spell if the roll fails. Targeting someone behind partial cover gives disadvantage. Hence losing your spell for the day because of cover. Like I said, it’s an edge case and one reason for separating casting and resistance rolls. But it just doesn’t make sense as it stands.
I saw it as making it harder to cast the spell on a target you can't make out completely, not that your trying to hit them like with an arrow or a thrown dagger. Magic is dangerous, think of the wish spell, so you need to get it right, and if you only have partial information it's easier to get it wrong.
Now the simplification, removing saving throws and to hits, is great. I do like that. But from now on I'm going to make a point in my explanations that the spell roll doesn't "replace" them. It just gives us a reason we don't need them.