I don't think you should lose control, but you should definitely be "strongly encouraged" to feed (like the werewolves in Bloodmoon). I still don't like that vampires lose their powers when they feed, which actually discourages you from feeding like a vampire should. Particularly now with Dawnguard, you don't get attacked as a monster for not feeding anymore either, so there's even less incentive to do so. From a gameplay perspective, this feels completely backwards.
That's the biggest reason I've never considered playing a vampire in Oblivion and Skyrim. To get vampire powers you have to not act like a vampire. If you act like a vampire, then you don't have any good vampire powers. Made worse by the fact that a single feed will undo all your powers, and there's no risk associated with feeding other than an assault charge if caught (hello, a monster just attacked you and could've turned you into a monster too, and all you give him is a fine?).
IMO, feeding on someone should damage their health. Do it too much in a short period of time, and they'll die. Getting caught feeding should give you a (temporary) death penalty. When you feed you'll grow strong with new powers, but also become more monstrous (with the strongest stage being an automatic attack-on-sight). Not feeding makes you weaker and more like a diseased person. One feeding for one stage of vampirism.
I never quite understood why people say the powers you receive as a vampire from not feeding are sole reasons why you shouldn't feed, I mean...the only thing you get from not feeding is more weakness to fire and more resistance to frost.
The powers themselves are strong indicators for you to feed.
I mean Embrace of shadows is there so incase you have terrible sneak you can still break into a house and bite some sleeping NPC and feed off him/her.
Like 100% of the Vampire powers you receive from not feeding all are there to help you feed if you svck at sneaking and such.
I mean they even gave Vampiric seduction a new function so you can feed on conscious people.
Then again...I like to roleplay my character as a vampire..ya' know, travel only at night, feed regularly, find a place to sleep during the day (making people your fledglings off the Volkihar radiant quests..helps a lot, always nice to have fledglings in cities who willingly offer you their coffins)
Makes it a lot more fun, in my opinion.
Also, the accidents of the Volkihar bloodline are what they call thin-bloods, if you are turned by Harkon or Serana you are instantly welcome in the clan.
I mean the Feral vampire in the undercroft of the Castle even references she was a accident and when she wanted to join they denied her and said if she returned they would kill her so she plotted her revenge in the undercroft..til you kill her.
(Sneak and stand still in sorta close proximity to her and she'll start talking to herself)
If you use Dead thrall on Volkihar vampires..the random enemy thin-blood ones they give you a similar story and the occasional hatred of the Volkihar clan for lording over them and looking down on them.
May have to travel a while with them though, they only go "Uuuuuuh" like a zombie for quite a while.
So there you go..some dialogue to prove Harkon's bloodline is the true Volkihar clan, unless you can prove that the thin-bloods hatred for the Volkihar clan is misguided somehow.