That's still peanuts for a corporation, assuming the corporation is profitable. Well, maybe not peanuts, but still not insurmountable. Valve has no trouble storing more game save states than that (some PC games save files can be relatively large, just my Witcher saves alone take up over 400 MB) with no limitations. And they don't even have, much less require, a monthly membership charge like PS+ to save in the cloud. MS has no limitations on the how much space your saves take up AFAIK (of course, they also run cloud services so can leverage that).
I think it's a very different business model; Valve and PSN. I'd guess that with Valve, every game purchase or rental (?) also includes the game-save allocation on the cloud. In other words; the more games you buy/rent, the more space you are paying for, so you have a scalable model. More purchases = more money = more (purchased) space. The storage scales perfectly with the increasing popularity, success and profits.
On PSN, it works differently. One user purchases one PSN (Plus) membership. That user can buy between zero and potentially infinite number of games that each have a 10.xx MB to potentially infinite large game-saves. So it doesn't scale with the number of games a user might buy. Even worse; Every free demo probably includes some form of game-save too. So the demands to game-save storage is a lot higher already. So a cap on game-save cloud storage is logical.
Of course, Sony could include it into their business-model too, by adding or alocating part of their royalties to the storage-demands, but it may be too late for that (because they perhaps didn't think of it sooner) and not every game that is purchased actually includes a Plus membership.
Then again, 100 million PSN Plus subscriptions might actually yield sufficient sums of money for an adequate cloud infrastructure. But it's not only the infrastructure that costs money, you got to think about bandwidth demands too. And you are likely spreading out your infrastructure to multiple localizations to keep latency for each of your regions down to a minimum. And with that money, you are also feeding your general storage for games, the whole multiplayer online servers etc.
As I said, I think 1 GB is actually quite a lot considering it's for game-saves. The problem I have is with the size of these game-saves. Even a 10.xx MB file is a lot of data when you think about it. It's perhaps not as simple, but 1 byte = 1 ASCII character, 1 million bytes = 1 million ASCII characters. 10 MB = 10 million ascii characters. From what I understand, an average novel holds about half a million to a million characters. That could be 10 novels in a single 10 MB file. If each game-save was 10MB, you could store 100 game-saves which would be plenty. Of course, once you include binary data, it gets data heavy, but how often are you saving binaries in game-saves? Most binary data in one form or another is already somewhere on your harddisk as game-data.
