Yes, the turbulent air makes it very difficult if you're against a half decent car and driver (see Vettel vs Alonso yesterday) on exactly the same strategy. Barrichello only got close to Schumacher thanks to his brand new tyres. There needs to be a cut down of this downforce, because on tracks like Hungaroring and Circuit de Monaco, the cars are designed to favour downforce over straight line speed.
Look to when Senna was around and the designs of cars weren't as complex to maximise grip.
http://www.youtube.com/watch?v=dv9DT7UXXt8 That is at Hungary.
On top of that, the refuelling ban is very strange when you think about it because fuel strategies make the field more unbalanced. You used to get drivers like Trulli who held up everyone and caused a train of cars where there was overtaking.
Edit: And this is proved by the usual bore fest which Bahrain produces every year. A circuit with 3 or 4 genuine opportunities to get into someones slipstream and overtake them and there is hardly any action.