Color is remarkably useful for fast recognition of objects. Take this famous experiment [4] that showed the existence of synesthesia. People without synesthesia take much longer to locate the 2s in the field of 5s. But people with synesthesia who perceive numbers to have color can find them trivially.
Anyway, as for this being offensive to you -- how is it any different than other facts like "short people have more difficulty reaching objects on high shelves" or "people born without a sense of smell cannot easily detect gas leaks?" These are simple facts, and there's nothing offensive about stating them.
[1] http://onlinelibrary.wiley.com/doi/10.1111/j.1444-0938.2002....
[2] http://www.ltrc.lsu.edu/TRB_82/TRB2003-000250.pdf
It reminds me of the research that was done a couple of decades ago now, about IQs among various ethnic groups in the US. This research was considered highly controversial and inappropriate, especially once it started showing there were in fact differences between those groups (though to the chagrin of the white supremacists, people of East Asian origin seemed to slightly outperform the Europeans). Now, to be sure, some of those involved did try to misuse these results, but the outrage went far beyond that.
It may seem obvious now, but these results ended up causing researchers to ask even more interesting questions. We know now that IQ is as much a measure of modernity as intelligence. It is definitely dependent on the environment of both the person taking the test, as the person writing it. People taking the same tests 100 years ago would have scored significantly lower, but it is not because they were less intelligent than we are.
These results also sometimes point out that some communities are in fact disadvantaged in their ability to achieve in the context of the modern world. However, no one likes to be confronted with the need for change since it's easier to become offended and sweep any existing issues under the rug.
I feel as a culture, we still have a lot of growing up to do.
Personally I hate the flashing yellow single light vs flashing red. Side by side I could probably tell a difference,but alone I'm never sure.