I had a D90 for many years and sold it for a D7100. However the D7100 body looks like it's made lightly or cheaper than the D90, is that so? The feel of the D90 was solid with hard plastic but with the D7100 it seems the plastic of the body and even the charger is cheaper. Is that true? I'm thinking I was ripped off.
According to Nikon's web site, there's some metal under that plastic.
The magnesium alloy employed for the top and rear covers endows the camera with high robustness and durability, despite its compact, lightweight body. The body is effectively sealed at various locations, ensuring weather-resistance and dust-prevention performance.
Although I wasn't able to find anything as convincing regarding the D90's construction, I found a number of references to "all plastic" construction, despite its weight.
I believe in this case, you can look at the light weight of the D7100 as a bonus rather than a detriment.