I thin it is great to have larger disk space, because that means that you can cram extras, videos, interviews, and obviously more game content into a game. Here is the thing, though: if a game takes a year to develop (by today's standards), it will fill up approximately 60-80% of an XBOX disc (ie Splinter Cell CT). That means either the team would have to be double the size to crank out double the amount in the same amount of time, or the same size team would take double as long to crank out double the amount. Bungie may have the money because MS is fronting them. Smaller companies? And Blu Ray is 8x the size of a regular DVD. Companies will have trouble filling 2x the size, let alone 8x. I agree with LowProfileWurm, there isn't enough time or content to really require a 30GB disc yet. I mean, the hard drive on the PS3 won't even be that big! (Which would be good for modding, cuz it means with a 120GB drive, you can only have like 3 games on it!
Not to mention load times would be horrible, even if all the data was uncompressed.