The D90 WAS a breakthrough for features, IQ, video as a DSLR first, Live View and was the first of Nikon(any brand) with a sensor that was essentially ISO'less so the noise was linearly proportional to the ISO. That meant someone could underexpose a few stops, for example when needing to freeze the subject by increasing shutter speed a few stops and end up with the same signal to noise ration when boosting exposure n post, that you would have gotten by exposing correctly at a slower shutter speed.
I still have the D90 and kit lens 18-105 and it has over 220,000 frames and in perfect condition. It actually had 1/2 stop better DR than the Crop flagship D300. I don't use it much but once in a while. My second camera for events is the D7000 which was also a groundbreaking camera at 16mpx with even better DR. My D800 has been flawless also and has 300,000 frames and although there is no logical reason to add another body, I have been feeling the urge. Maybe D850 or Z7.