You're not alone in posing this question to be sure.
The 18-55 and 55-200 actually get excellent reviews optically, and even if purchased separately from the body, represent great value for money. I applaud Nikon for not bundling cheap optics with their kits.
Beyond the economic and image quality advantages, they're also pretty compact. Many people find they need nothing more, except maybe a 35mm f/1.8 as others here have already mentioned. That's a bargain, too, for $200.
My old Olympus EV-500 setup had something similar to this - a 14-45mm and a 40-150mm. Optically, these are fantastic lenses. The only beef I had with them is that for casual, not-sure-what's-coming-up-next shooting, I never seemed to have the lens I needed on the camera.
I can't tell you how aggravating it is to have to swap out lenses all the time.
Which brings us to the classic and dreaded trade-off dilemma we all face: Everything is a compromise. You can have reasonable quality and low price, but at the expense of convenience... You can have convenience, but at the expense of ultimate quality and low price... You can have excellent quality, but at the expense of convenience and low price.
It sounds like a cop out, but it really does depend upon how you shoot and your priorities.
The 18-200, for instance, is very popular. Depending upon who you read/talk to, its quality seems to range from acceptable to very good. The convenience of having that kind of range is hard to argue against. On the downside, it's not as sharp as some zooms with a narrower range (and certainly not as sharp as a good, fast prime) and it's pricey.
Will you notice the difference in image quality? Maybe. Will you be bothered by those differences? Perhaps. You probably won't be on-screen or in smaller prints. You might be if you print large or crop excessively.
Then again, if you don't have the right lens on your camera and need to swap out, the opportunity to make your picture could be gone, in which case image quality is a moot point, isn't it?
If budget is the primary driver in this decision, I wouldn't hesitate to go with the 18-55 / 55-200 combo for a minute. Add a 35mm f/1.8 and you're in great shape without breaking the bank.
If you have the budget and value convenience, check out the 18-200.
Or, look into the 18-105, live with it for awhile, and see if you even have the need for something longer on the tele end. It offers a nice wide range and good image quality, and other than being a bit slow aperture-wise, it is a fine choice for portraits. I didn't see a mention of wildlife shooting as a priority in your post, so you may not need anything beyond 105. If you find you do, you could then look at something like the 55-200, 55-300, or better still, the 70-300.