Yes, I agree. If you are purchasing a 1080p display to last somewhere around 10 years or so it probably would be prudent to look for something that accepts 1080p native input, especially since some manufacturers offer them right now. It is true that there is not much 1080p source material available today but I'm relatively sure this will change within a year or two. The first salvo might be high definition DVDs (either Blu-Ray or HD-DVD or whatever) but one never knows if there will be 1080p connection problems due to all the copyright protection issues. I predict that it will be a bit rough at first (connecting 1080p output to 1080p input from commercial sources) because of this. For example, I have been told that some Cable boxes from Scientific Atlanta that provide 1080p output on an experimental basis have trouble interfacing with some 1080p input capable displays since the display can't interpret the 1080p signal as being a valid one and all you get is blue screen (or green screen) with an error message stating that the source material is copyrighted.
Some people are willing to forego native 1080p input because the sets will scale up other resolutions to 1080p for display and it looks very, very good by today's standards. And since there is an outside chance that true 1080p sources, on a large scale, might be a bit further away than we think they are willing to buy 1080p sets that only scale to 1080p. That thinking involves wanting the best possible picture right now without being concerned with possible future sources. In those cases, the buyer will live with the lack of 1080p input and deal with this when 1080p native sources are the norm. It's called "upgrading."
I'm torn. On one hand I'd like a set that offers 1080p input. On the other hand that SONY SXRD 50" set looks very sweet! I predict that this will be one of the more confusing aspects of Home Video over the next several years as more people acquire HD hardware.