Someone with a good number of EF-S lenses will have to answer, but from what I understand, there are many high quality EF-S lenses that are optically on par with L lenses.The efs 15-85 and 17-55 f/2.8 are both very good, a lot of people say the 17-55 is better than the 24-105 f/4L for the same focal length, IS, and effective aperture.
But just being an 'L' doesn't especially mean it's flawlessly perfect, look at the corner softness of the 17-40L, 35/1.4L, 24/1.4L. Look at the field curvature of the 24-70/2.8L. Look at the barrelling of the 28-300L @28mm. Compare the MTF sharpness of the 50/1.4 and 50/1.2L (yes, the f/1.4 has its own problems though).
But then, look at the release dates of some of those lenses. Also, pushing the boundaries of useful lens design leads to compromises, like the ultra-fast apertures, or extreme zoom ranges. They'll get better with new revisions, and it's not like any other company can do any better (and make it affordable).
Some say the 17-55 f/2.8 should have been 'L' designated, for its quality. Maybe, but what's the difference? If it's L, that doesn't mean it will automatically be weather-sealed. And weather-sealing is probably the only L-feature that lens lacks. Adding a red-ring won't mean anything to anything except the price (and maybe the stealability).
Also consider, it came out before the 7D. Before the 7D, nothing APS-C was sealed (to that degree at least). 7D is a sports/wildlife camera, not landscapes. Buying a 7D for sports/wildlife generally entails a weather-sealed telephoto L lens, 70-200 IS, 70-300L, Big White Primes etc. Buying any less is a waste (i found that out with the 70-300nonL).
Sure, you _can_ use the 7D for landscapes, i've taken some good ones with my 15-85. But the 5D2 in the same spot will probably take a sharper shot in most circumstances (and i can't afford a 5D2). But still, the 7D is not a 'dedicated' landscaper, it has its specialties elsewhere...
because a red ring and a white square would look weird together.Doesn't look so weird with my 70-300L on my 7D.
How about an EFs L with a white ring?
Otherwise, get L prime lenses and use them on your 7D.Yep, that's surely not a mistake by their marketing department, that's what they want us to do no doubt...