Valid, but I'm still more concerned about "why should I spend a spell slot to deal 1d12 damage, when a Cantrip is 2d10".
Hmm, I actually used Witch Bolt quite a lot in my early playthroughs, until I realised that upcasting applies to initial damage only. I think it is a decent option early on, but without scaling of guaranteed damage I don't see myself using it past level 4.
