You would have to blow up a print at least three fold for it to be large enough for noise to exhibit like it might at 100% on-screen. The simple fact of the matter is, the VAST MAJORITY of viewing contexts require downsizing, usually significant downsizing or increases to resolution density, relative to a 100% crop view on a computer screen. The only time you are actually enlarging any viewing context beyond that scope is with prints larger than 52"x35" (for the 7D anyway), at which point image pixels in print are about the same size as on a screen. Most of the time, enlargements of such scale are done very carefully, with meticulous care around noise and sharpness, so noise is rarely as visible on screen as it is in such a large print.
The only time the levels of noise we have today in current-generation cameras (7D, 60D, 600D, even 5D II) exhibit as a problem is when viewed at 100% crop on a computer. Outside of those who tend to obsess over quality at 100% crop, viewing any photo in that way is impractical and unrealistic. @KeithR's sample photos, while they do appear to be downsized a bit, also demonstrate a REALISTIC viewing context, and thats where any photo's IS should be evaluated...in realistic context.
I know that you believe what you are saying and trying to be helpful, but I still think that you don't understand the crux of the problem. Let me see if I can break it down for you.
1. I can see the noise from an ISO 100 shot on my 7D when looking at the entire photo on my 27" screen. That is... NOT a 100% crop. Quit saying that noise is only an issue at 100%.
2. Next you will say "calibrate your monitor!". That has nothing to do with it... as my XSi shots look fine when viewing the whole image on the screen.
2.5 (Ninja Edit) Extreme resolution monitors are on the horizon (most likely this year). There are already talks of a 2880x1800 Macbook Pro... and an iMac could come out with 5120x2800! At those resolutions npise is going to start to be easily visible in a lot of photos!
3. Cropping: one of the main reasons to move up to a higher MP is so you can crop a bit closer. If your image has a ton of noise in it that negates a lot of your ability to crop.
4. Different people have different purposes for their photography. If you are doing portraits, you might leave the final picture a bit soft so as to downplay facial blemishes. However, if you are shooting landscapes you want to bring out every detail and that means "sharpening". If there is a ton of noise hanging around it might not matter to the person doing portraits, however if you are trying to sharpen tiny details in your photo (that you bought an 18MP camera to capture) noise makes life extremely difficult.
5. You keep claiming that all anyone does is look at tiny versions of your photos. I will mostly agree with that (but add a caveat about cropping - and how that effectively means that even viewers of your prints are "zoomed in"). However, what if that didn't have to be the case??
Personally, I upload full resolution jpegs to Flickr. If someone is so inclined, they can view it at full resolution and zoom in to see detail in my landscapes. Now, I agree that most people probably don't do that... But just think about if you could capture perfectly noise free images: you could encourage people to explore the full res versions of your photos, giving a new, dynamic way to enjoy your photography.
I guess my problem with your philosophy on noise boils down to this: You, just like every other luddite throughout history continue to claim that "What we have is good enough!". The problem is that you are WRONG and will be proven so as technology advances. In 5 years we'll wonder about how we put up with these noisy machines as we look forward to advances on our 45MP mirrorless pieces of awesome that we use in ways you cannot even fathom right now and you will still be saying things like "Why do you need something better than 45MP!"...
I have been entirely too negative in this post so I will leave you all with a link to a set of photos of mine on Flickr. These were taken with My XSi and have the full res versions of the images there... So feel free to view them that way!http://www.flickr.com/photos/friedmud/sets/72157628014191618/