You really expected Bluray disc format not to be used to the fullest ie. games to be smaller than 45 GB? Especially when the game includes a lot of cinematics. I once thought of buying games and ripping them to a HDD, but the effort of making it possible is just too big a hassle. My game collection is also quite big so I'd end up with quite a few 1TB/2TB drives to fit them all.
tl;dr: Games are big, it's sometimes easier to just buy them since quite a few older games cost only around $10 anymore. HDD are cheap, but usually they end up being about the same price when DL costs (electricity, bandwidth, etc) are considered..