^^^
I know that the Vibe isn't included in alot of TSBs that the Matrix is involved in. Some Vibe owners on the Matrixowners forum and TN have just overfilled their existing engines by 1/2 quart (about 3/8" over the full line on the old dipstick) with no issues at all.
Technically, this can be also applied to 8th gen Corollas/Prism with the 1ZZ-FE as well - but I believe this was done on the 9th gen models in anticipation of running the thinner 5w-20 motor oil starting with the 2006 model years (5w-20 approved for earlier years as well).
I could see this as a band-aid fix for oil consumption. Note that the old (3.7qt) oil level itself will have no bearing on oil consumption due to stuck rings, but the degradation of that oil, due to a limited supply of oil available in the engine, will require extensive oil quality monitoring that is likely not possible with most owners. Increasing 1/2 quart doesn't sound like much, but just like with extended oil change intervals, even a small amount of make up oil (fresh oil) will greatly boost the longevity of the oil being used. So this is brought out as more of a "safety" cushion than anything else.
Unfortunate that is came about so late - the 1ZZ-FE is a pretty decent engine, just the design of it and how people drive the car, how Toyota is pushing lower maintenance - puts a lot of strain on the oil. Aftermarket has recognized this and there are oil pans with kickouts, enhance oil cooling, and baffling to increase oil capacity to 6 quarts and make sure oil gets to the oil pickup.