It costs more... has snob appeal for some.

It performs about one f/stop better in low light than APS-C (there’s less noise, better color) and nearly two stops better than Micro 4/3.

Manufacturers can cram more sensor sites on the imaging chip. This allows bigger prints, tighter cropping, or some of each.

You use a longer lens to get the same field of view at the same distance from a subject. This creates shallower depth of field at the same aperture.

These qualities may, or may not, appeal to you. FF gear is bigger and heavier than APS-C, and MUCH bigger and heavier than Micro 4/3. It is generally more expensive.

There is nothing wrong with any format, so long as it serves its purpose for your needs. Get what makes sense.

Most Photo Labs will tell you that <5% of prints sold are larger than 11x14. Over 90% of images are bound for Internet sharing sites (Facebook, Instagram, etc.). Few of us spend much of our time photographing in dark places.

That said, if you want room to crop, or if you make LARGE landscape images, or if you photograph scenes that will be printed huge and examined from a foot away, full frame gear becomes desirable.

Today cropped cameras do as well as full frame, are less expensive and last a lifetime. In the beginning, when buying a full frame camera cost an eye and a leg their low light performance was superior to cropped sensors and photographers, used to shoot with film, saw the advantage to them of using a camera that offered the same view as a 35mm camera with the same lenses used for film. As you know, eventually many lenses for the FX format complimented the camera and the professional photographer had now a camera with lenses to cope with any situation.
In the meantime progress in technology began to make the gap narrower between DX and FX bodies. The new cameras are excellent in low light and there are now lenses of excellent quality to also cope with any situation. The advantage of the "digital factor" is still important for those photographers that engage in sports and wildlife photography often. Using the DX format they have with those lenses more reach.
I have never used one but I know the D7200 is an excellent camera and paired with good optics it is a very competent tool. I am still using a D7000 and I am very happy with it since it fits my photographic style.
Stay with your D7200.

It costs more... has snob appeal for some.

It performs about one f/stop better in low light than APS-C (there’s less noise, better color) and nearly two stops better than Micro 4/3.

Manufacturers can cram more sensor sites on the imaging chip. This allows bigger prints, tighter cropping, or some of each.

You use a longer lens to get the same field of view at the same distance from a subject. This creates shallower depth of field at the same aperture.

These qualities may, or may not, appeal to you. FF gear is bigger and heavier than APS-C, and MUCH bigger and heavier than Micro 4/3. It is generally more expensive.

There is nothing wrong with any format, so long as it serves its purpose for your needs. Get what makes sense.

Most Photo Labs will tell you that <5% of prints sold are larger than 11x14. Over 90% of images are bound for Internet sharing sites (Facebook, Instagram, etc.). Few of us spend much of our time photographing in dark places.

That said, if you want room to crop, or if you make LARGE landscape images, or if you photograph scenes that will be printed huge and examined from a foot away, full frame gear becomes desirable.

For uncropped images, a bigger sensor is magnified less than a crop sensor, which usually has a positive impact.

Image quality differences are most notable on small prit's viewed up close. It's not about making big prints. With as little as 8 mp you can make entire wall-sized murals. This link busts some misconceptions about print resulution and print size.

http://www.photokaboom.com/photography/learn/printing/resolution/1_which_resolution_print_size_viewing_distance.htm

Until recently, only the full frame lenses were "fast" ie., larger maximum apertures.

Because of shrines losses due to diffraction, the full frame sensor has the least negative impact when using smaller apertures. One can use a full frame camera at F11 and still be able to record extremely fine detail, while the APS-C camera will start to lose fine detail at F8 and the M4/3 at F5.6.

For studio, landscape and architectural/real estate photography, you can get a variety of lenses that offer tilt and shift. While you can use them on APS-C cameras, the focal lengths that these are available in are really optimized for full frame.

Build quality is usually better on full frame cameras and lenses, but as the industry consolidates on smaller cameras and the public demands better quality, there are more options.

These are very broad generalizations. I use both full frame and a very good bridge camera with a 1" sensor.

Don't believe the myths that you need more mega pixels to make larger prints, or that you can't make a giant print from a tiny sensor. Just take a look around, and you'll see Apple bilboards that show images taken with their iPhones, and they look great.