If you really look at the DSLR age, they are a pretty new equipment. Previously, cam makers like Nikon, canon, Pentax , or Olympus, they just have to concentrate on making the cam body, the film part was left to players like Fujifilm, Kodak, Agfa and what you have. Suddenly, with the conversion to digital, the cam makers got to learn how to make "digital film" , and in fairness it has only been about 10, 15 years. That's why its common to have cases whereby a latest model does not necessarily means better performance then the previous one.the manufacturers are still tweaking their products. as for having more features, believe me, this is the cheapest part of the products.
I also caught into this b4, but after taking a few shoot at alanphoto & comparing D5000 + D90.
And I was impress with D90, so settle down with it.