The problem is not just iCal but ranges from App Store to xSan. Apple has placed style above usability and is ignoring what the customers are saying about their interface.
What baffles me is how they can pass the Federal Governments accessibility testing requirements. Switching to white on black interface even for a moment adds another layer of problems:
1) It can be disorienting visually, particuliarly if you are using the zoom feature.
2) It interrupts the work flow by adding yet another task or adaptation to deal with on a busy screen.
3) It removes the visual cues that color provides for everyone. There has always been a myth that those with low vision can see and use pictures, books, or GUI with less strain if high contrast black and white color schemes are used. This is not true of most people with lower visual accuity. Without color many things can become just a jumble of white and black lines that take more time to interpret.
This does not even address the problem that the average person has in seeing this lite grey text. I have read to many complaints about it on the web from people who are not visually impaired believe this in an isolated problem. According to most people that I have spoken to the grey text does not add to the experience of using a Mac. In the long run, they say it detracts from the user experience because of the added strain.
When I quaried Apple tech support about this problem I recieved what seemed a canned response. The change in the interface was towards a more "minimalist" style and that was the overall trend in the industry. Funny thing is I don't see this extensive use of lite grey or low contrast text in the Windows Servers and Windows 7 machines that I support each day. I don't know if this means Microsoft is listening more to its customers or they are more hardcore down to earth bussiness oriented, as opposed to style oriented.
I hope that at some point those in charge at Apple realize that these are not minor stylistic issues for us. It can mean the difference in getting a job done in a timely fashion and, thus, keeping our job, or being unemployed.
Apple, the decisions you make affect real people. In this case it has caused harm to those who have no other good choice than to use your interface.
Frankly guys, I don't think those who make these decisions care what harm they have done.