The point of using one (or many) large files is usually to get better disk throughput.
Also Darkstar, why would you need to have the files uncompress / unpack to the disk? Why can't you uncompress / unpack directly into memory? (Well, maybe this is an issue with Enigma actually)
For several large files that might apply, for games that use so many smaller files that would be true. Better to have single file resources than thousands of small files scattered all over the place.
I guess it's more convenience than necessity it all depends on the developer. Nowadays with blazzing fast memory and disk access, most people would really not notice any difference in random access considering some games pre-load those and would not affect gameplay otherwise.
As far as compression, I don't mind my resource not be compressed, but if I use many I would encrypt and store them together. If there was a way to binary read from files starting at pos X to end pos, store that into a variable or a buffer and add from a buffer, that would skip having to READ / WRITE / RE-READ, instead it would be READ,you would skip write and re-read.
Example.
SCENERY.RES
binary read from pos 10000 to 25000
storing into a buffer
add background image from stored buffer
or add sprite, video, sound, music, from buffer, etc.
So this would allow direct to memory reading. Imagine
the disk access you would save (writing back + re-reading) when talking about large resource file, and big games the speed increase would be interesting.
From what I was told game maker has some form of dynamic handling, but I think it is shitty at best, I want to be able to handle my resources the way I want them and not the way they tell me to !