People may be perfectly happy with simply doing email, but pcs are REQUIRED for school, REQUIRED for work, and required to do more then be a hillbilly in a trailer park.
Think for one second: Without a pc that has an ip address, you can't search things like google maps, you can't (safetly) do online banking, you cannot buy things either (unless you realyl feel like having your identity stolen by having all of your information on a cloud), etc.
This idea is basically like going back to the 70's. If email/twiter/facebook is all pcs were good for, then we should just go back to mail, metting people at bars, etc.
This idea doesn't account for all the multitudes of purposes that pcs are used for. Go apply for college and try to explain to them that your pc is on the cloud.
In short, stop reading blogs from the cult of mac.
This has nothing to do with macs. All could easily be applied to any device.
You are using the cloud all the time. All the activities you mentioned are internet activitie:
1. Google maps - you are using Googles storage and servers you just are a display device. You do not have satellite maps downloaded to your device for this, it is all in the google cloud.
2. Banking - the bank's database is not downloaded to your pc, you are again just the display device
3. Online shopping - again just the display.
In fact not one activity you mentioned uses your PC for more than a display.
The thing that makes the iPad world (but it could be android or other world) is that the apps are prescreened and hopefully work as promised. The model is small (hopefully cheap) add ons to your device. They basically work.
It will be quite a while before everything you can do on a PC can be done on one of these devices. But, this is the turning point. Right now it is at the 80/20 rule point. 80% of PC users could probably use one of these devices and never miss their PC. This is why these products are coming to market now, it is finally at the point that they are useable.
As far as the cult of Apple point, Steve Jobs appears to have once again seen the correct time to enter a market. It is not like any of the technology is new or revolutionary like the Apple hype would have you believe, it is just the time where internet connections, hardware technology, and component prices are at the right stage for the market to be successful.