Newer is better in terms of the technology and performance. So if you need better high ISO performance or more pixels than your D700 then move to the D600 or D800. But if your D700 allows you to take the images you want, then there is little reason to upgrade. My experience (since starting back in the olden days with the D1) is that generally the new bodies expand the envelop of performance over the previous bodies. But where that performance overlaps with the previous model there is little to no noticeable improvement.
Quick example - I have a small basement studio and my D2x, D3, and now D4 have been used there. When using my monolights and at base ISOs there is absolutely no advantage in using the newer bodies. So if your D700 does everything you need, why change it out?
Of course if you do upgrade you may find that the performance improvements in the newer body leads you to new areas of interest. When I had my D2hs and D2x there were venues I did not shoot in as the camera's usuable high ISO performance (1600 max) did not permit it. I unconsciously tailored my shooting to match the capabilities of my equipment. I now find that I can't live without my D4's ISO 12800 performance (which is better than 6400 on my D700).
So I guess my answer to your question "Am I crazy?" is the one my lawyer often gives me "It depends"