This is not unique to YVR.
Using Nexus to enter the USA has always required the 'blue card' to be filled out, whether you're at YVR, YYZ or YWherever. When you received your Nexus card you should have been informed of this.
YVR is my home airport. When I fly I fill out a blue card a day or two before. That way, if GE is out of order I can just slide over and use Nexus. If GE is working the card just stays in my bag, as it's not needed.
As for CATSA, I find the queues move much faster than they do with the TSA. As for shoes & belts, blame the USA for that one - The US govt. requires that of CATSA. If you Canada domestic or Canada international, the shoes and belt can stay on.