Okay. I have received some feedback on the experiment I have been running (see post below this one).
From what I could determine, there are two negative side effects from changing the length of the week number events. 1) All days are marked as busy (all days are bold in the mini-calendar). Previously only the first day in the week was marked as busy. 2) The week numbers appear on every day in the Agenda view.
Despite of this, I have decided that the benefits outweigh the side effects, and I will apply this change to all week numbers in the coming days.
For those of you who despise this change, there is a remedy! You can simply switch to Google's own week number calendar (instructions above). Their calendar is exactly the same as my calendar was before, with the exception of a different icon.
My final thoughts on this is that I don't think Google has successfully added week numbers to Google Calendar. I think week numbers need to be integrated in the same manner as normal date numbers. Any "solution" that requires an extra calendar will be flawed in some way. My hopes that Google will make week numbers a first class citizen is unfortunately very low.