The “buy lenses, not bodies” rule is still useful, but it isn’t absolute. Modern DSLR bodies matter more than they used to because sensor quality, autofocus, controls, and other features can significantly affect what you can shoot.

If you can afford the better body and its features matter to you, choosing it can make sense. A higher-tier body may also offer better construction, more metal, weather sealing, and longer shutter life.

That said, planning for a DSLR body to last 15–20 years is unrealistic for most users. Mechanical wear (especially shutter actuations) and the long-term reliability of electronics make that a very long service life to expect, even from well-built cameras.

So the usual advice still applies: lenses tend to hold value and remain useful longer than bodies. If your main reason for spending more is to make the body last 15–20 years, that’s probably not the best justification. If you want the D7000 because of its better features and the more useful kit lens, that’s a stronger reason. Otherwise, buying the less expensive body and saving money for lenses—or a future replacement body—may be the smarter long-term choice.