That's simply not true. The EU has over time handed more and more power away from the council and commission and to the parliament. There is a demonstrated will to hand more power to parliament at the cost of the council and commission and any treaty changes to do so (accompanied by according constitutional changes) would reduce sovereignty while reducing central control.

As it stands, the Treaty of Lisbon went about as far as it could in handing additional powers to the EU Parliament while triggering the minimal number of constitutional changes for member parliaments, and look at the circus that turned into. And that was first after the attempt at a constitution failed.

The centralisation you worry about already happened many years ago, and the sovereignty issue is now largely the blocker to devolving more that power to the EU parliament, and after the trouble getting the Treaty of Lisbon through there's little appetite to take another round anytime soon.

That Lisbon has given substantially sharpened teeth to Parliament has been demonstrated repeatedly, with both the Commission and Council of Ministers having been forced to backtrack or compromise in areas where they previously would have been able to do what they wanted.