Most of it comes down to sloppy code, usually caused by strict deadlines. These days simple things like vertical text-scrollers are put into animations, since rendering such an animation is easier and quicker then actually coding such a thing (which looks better and uses much less resources).
Companies want to push out products and make money on them as quickly as possible and they don't care if that means you need a couple of megabytes of extra memory/harddisk space.
I also dislike the fact that each game on the PC needs installing to the harddisk, which takes hundreds of megabytes of harddisk space and then the game still needs the CD's to start up. Most games can easily be run straight from CD... I hope that'll happen on Amiga.... it would be great if they even make the CD's bootable, so you can start up your Amiga, insert the CD and it will run the game without having to install it... or boot from harddisk first.
Regards,
Onno