These 24 GB mandatory install even if you buy the retail copy are absolutly ridiculous,especially since I didn't notice any improvements..loading are just as long etc etc...what the hell is this for.
I've noticed load times being pretty damn good on PS4. And when you consider it has 16x the memory of the PS3, that is pretty impressive.
Basically no practical way to read the game data off the bluray drive and not have 5 minute load times - HDD is the only solution.
And the way PS4 does it - it'll start installing as soon as you put the disc in, even before you've sat back down again - and installing as you play, means it is as seamless as it can possibly be.