In this case, if you cast Wall of Fire to block a corridor, and set it up such that it does no damage to the enemy (or anyone) when it goes up, I'd allow it, and I think falls outside the "target" restriction. If the enemy then walks into it on their turn, or whatever, that doesn't matter. When the spell went up, no one was "targeted or harmed". I think your description of casting to assist in running away likely matches up with RAI. It at least feels right to me.My question mostly lies at the intersection of these two things. What about a situation where you're dropping wall of fire in order to prevent people from following you? You don't want to target any of them--you WANT them to stay AWAY from the fire, because that lets you get away.
Does "target" care about the psychology of the caster? It seems to me that "drop something to cover my butt so I can turn tail and run" is a perfectly reasonable thing to do when you feel "hopeless," yet it also seems like the natural-language meaning of the description of that effect is that you can't really cast damaging spells or SoD/SoS spells, regardless of how they do their damage or cause someone to die/suck.
Natural language can work just fine if folks don't try to poke holes in it, interpret it to their advantage, or seek loopholes (you know, all the things that can go into playing any game - I just happen to be not great at that skill set). If you're playing DnD in a "non-competitive" (and I hate to use that phrase, as its all supposed to be cooperative) manner, then natural language works great. In my experience, when my players demand the combat be drawn up, squares start to be counted, and every position of every spell and character starts to matter, then we've crossed the rubicon into miniature wargame, and then the precise language starts to matter...