At least you have a decent amount of displacement. My Alfa Spider… 2.0l engine, almost 8l of oil.
Ok, serious response to this. I used to feel this way about low displacement engines having large oil sumps. If you look, it's mostly European engines that do this. There are several factors that can cause a need or desire for this.
1) Oil change interval. More oil means that the contaminants spread out over a larger quantity of oil, so your oil isn't as contaminated per unit volume as it's running through the engine. Although I don't think many if anyone ever did this at the time, my 1992 XJS owner's manual actually allowed for 7,500 mile oil changes with its 12 quart sump.
2) Not needing to top off oil. This is basically a bygone reason, but in the old days of engines leaking or burning lots of oil (Jaguar, as one common example) a big sump could mean you don't run out of oil as quickly.
3) Necessary oil volume so you don't run out of oil due to engine RPM. Oil level within an oil pan is not a static item. While the engine is running, oil is being pumped up through the engine, through the oil cavities, and then has to drain back down into the pan. Obviously these passages don't go dry when you shut the engine off, but especially at high revs, areas like valvetrain can have a lot of oil sitting around that hasn't drained down yet, and that reduces the actual amount of oil in an oil pan.
4) Necessary oil volume so you don't run out of oil during high-G maneuvers. Hard turns, hard acceleration, and hard braking all will make oil move around in the oil pan. Although most high-performance cars have baffled pans of some sort to try to make sure the oil pump never runs out, this is still something that needs to be accounted for. For my Cobra, I bought a baffled racing pan, which holds something on the range of 9-13 quarts for a Ford 351 (I honestly forget the exact number and I've only filled it twice, last time being almost a year ago). Note that a standard pan is going to be about 5, but the biggest reason for the increased capacity on the racing pan is to make sure the oil pickup never runs dry.
Engines are dynamic things, although we usually work on them statically.
