First off, watch this commercial.
Secondly, what is the first thing that popped in your head after watching it? Was it "wait... is that little boy playing with a... oh my God"? Or was it "that was freaking hilarious"?
Either way, the commercial got your attention. IKEA used the tactic of humor to grab a hold of you. There isn't necessarily a lot of the actual items from IKEA in the ad but they give you a reason to buy storage, even if it was a reason that's completely out there.
IKEA's main audience is college-age adult to young professionals. I don't think that 12 year old school children or 72 year old grandparents are going to get the humor of the ad. But for those in their late teens to late thirties, it's going to get to them. When they decide that they need storage of some kind, this commercial is going to stick in their minds because of the humor and not really the products.
Advertisers want their advertisements to be memorable. As long as the brand name stands out, the recall is better later on. This IKEA commercial combines perfectly a humorous, memorable situation with the brand name of the IKEA. If the two don't tie together, it's going to be harder for people to connect in recall, thus losing the point of a memorable commercial.