That's not the same thing, from the second the PS3 hit the standard output was 720p. If for whatever reason Sony decided to drop 720p support it would mean 95% of the current PS3 catalogue being scrapped. That would be insane, and would never happen.
And it's not that the PS3 doesn't output 1080i, it does, when the software supports it, so to say "supports 480p, 720p, and 1080p only." would be wrong because it actually supports 480i 480p 576i 576p 720i 720p 1080i 1080p, but it depends on the source.
That is the same for all the BD and HD DVD systems, the only difference is they include scalers (for the most part).
Maybe Sony should put on the box "Warning, does not include resolution scaler for PS3 games, only for Blu-Ray films, DVD's and PS1 and PS2 games (on current firmware)".
But anyone who would know what that means would more then likely be wise enough to research the product before buying it.
I'm not saying Sony shouldn't include a scaler, I think it should have been there from day one, I'm saying they shouldn't have to.