I like numbering the platforms. There are times (admittedly rare) when it can be helpful like when trains are wrong railing plus the paint isn't expensive.
You must not have any graphic design experience then
Again, it's an island station. THERE IS ONLY ONE PLATFORM.
I understand that there's only one platform, but I've twice seen people mistakenly get on an Expo train and insist that the Expo train was at fault for arriving on the blue line platform. People need all the help that they can get. It also gives some consistency along the line. Expo has plenty of side platforms so it makes sense to label them all the same.