Installing games

I feel slightly retarded, but I've had the PS3 for almost 8 months now and I still don't understand the use of installing games. It's not like they load faster or anything... when I rented Resident Evil 5, it ran very much like it does in my X360, despite the installation.

Can anyone please explain?

I suppose the main benefit is that it saves wear and tear on your disc drive, as it doesn't need to access the disc so frequently. Performance-wise, on a DVD, the benefits are probably negligible, but for blu-ray games like Metal Gear Solid 4, Uncharted 2, Heavy Rain and God Of War III, the addition of the ability to locate a large part of the game on the local hard disk means a lot less work on your disc drive and I'd also imagine considerably faster loading times.