Ever thought that maybe they were - maybe the bumps you're experiencing on your flight are the least severe in the air you're traveling through. It would cost them more money to fly through dirty air (decreased aerodynamics) than it would be for them to re-route a little.

In fact I was just on a flight with DL last month where they did a significant re-route in order to avoid a storm - and guess what, we even arrived early!

You're being a little conspiracy theory nutty I think - take the tin foil hat off and enjoy some fresh air.