I played a mage in WoW so targeted AoE's are nothing new to me. However, those sorts of moves were easy and made sense on a ranged character where you could see everything and didn't have to move that often. Just imagine casting Flamestrike in melee every 15 seconds. It would be really annoying.
Maybe I'm just more rhythmically focused than most people, but on caster classes your moves seem more staccato due to the cast times, so stopping to position and cast an AoE didn't seem off beat. However, Melee classes have always felt more legato for me. They need to flow seamlessly from move to move as you constantly dance around the battlefield, avoiding AoE and what not.
So to answer your question, DF feels "jarring" because it is a large staccato moment in the middle of an otherwise legato playstyle. I use my mouse to move and position mostly, so when I need to target an AoE with it I feel like I lose some control over my motion, like missing a step in a dance.
That's what I mean by "jarring"
Edit: you not doing the research isn't a reason for it to be a heavy melee class. - Invitcted
In response to that statement, I was originally intending to play this class as a tank, but ended up switching to dps at around lvl 40 because a good friend of mine wanted to play a jug tank. And I actually LIKE melee caster spell sword types. My favorite class in WoW was a Death Knight for that very reason, and I love making tanky mages in the elderscrolls games who carry around giant swords : )
That said, the problem I have with both Madness and deception is, ironically, that they are too polar. Deception is almost all melee focused with very few spells and madness is all spells with, lets be honest, very little melee. My favorite dps spec so far was the old deception / madness hybrind that speced for both induction and raze. That was PERFECT in my opinion, a beautiful melding of spell and sword. DF was a part of that, but it didn't feel like there was no reason to be in melee due to the strong synergy between induction, raze, and unearthed knowledge.