Sure, but if you have a download cap or a limit, you maybe shouldn't be investing in a games console without first investing in a decent internet provider first. For one thing, any time you go online with your console, which most people are forced to do as standard, that's forcing you higher to your cap.
As for the HDD issue, if the max is, let's say 50GB, that's ten games on your console at any given time. Let's say nine just to be safe, so you have some spare room for your saved games and such. Do you play nine games at all times, or do you maybe keep one or two good multiplayer games that are constantly going in and out of your tray, and a handful of story based games which you won't really play once you've finished them?
Not to mention that in this day and age, if you're not already investing an external hard drive, I have to advise that you do, even if its just to back your important things up. At the prices today you can easily pick up a 1TB drive for the price of the latest CoD.
Online gaming doesn't effect your download cap which is what most people will likely have if they have any restrictions. Another common restriction is useage, some people can be slowed down during peak hours. However most of these packages are suitable for online gaming, my old internet package had a moderate download cap and I was supposed to be slowed down during peak times but I never noticed any major differences. Then we upgraded.
In fairness, most people who have internet restrictions will go with Console because of the fact you shouldn't have any major downloads, apart from system updates and patches, downloads on consoles are limited to what you buy. Whereas PC, generally speaking, you'll be downloading more often either for games on Steam or other sites. So console is an option, so what you're saying isn't really valid.
So let's call it 9 games like you said. Now I don't play 9 games at once but what I don't want to have to do is download 50GB again and again and again and again for every instance where I might want to play a game. For example I recently went back to Killzone shadowfall which has a 42GB install patch, so god knows what the overall size would be if it was a digital copy. I have a decent internet speed but even so, that would take awhile. And again....those with download caps or slow internet would take quite awhile.
The last part of your post, I don't have anything to say to but at the same time, its not something people will want to do.
I'll say again,
On console there is very little benefit to digital games.
They cost more
They take up larger amounts of room on my HDD
I can't sell them
I can't give them to friends
If digital games were cheaper than what I could get out of Asda (average game price in Asda = £42) e.g. £30 I would over look the above, but sadly it isn't and until they make digital prices competitive with what I can get in a retailer, digital will always remain the obsolete option for console gamers who do like to make sure they get a good deal for their money. For console gamers who are overly flushed with cash, they won't care but I'm sure a good 95% of us aren't flushed with cash all the time so....