The killer app is youtube/google maps on a phone. You dismiss that as a gimmick so you wont ever get it. You dont have people around you who need instant access to emails and evidently dont have people who use youtube a lot so you dont see either as useful. Maybe this is a generation gap thing but I suspect Im closer to your generation than the youth of today. Almost everyone I work with uses blackberrys and every time we work off site everyone else is using them too.
These berry users dont all run companies but they would probably pick their blackberry up in a fire before they went for their bag. For some people it is necessary - if you dont see that then I agree youll not see why its useful. Lots of people rely on emails for more than getting milk. Clearly your emails arent of high priority.
Im with Sam tbh.
I cant think of a single person that needs mission critical email response.
Your mates asking you to pick up a bottle of milk on the way home doesnt need an instant reply. Anything that urgent can be sorted via a text or better yet, the real use of the phone: A phonecall! 
Nope - heres an example. I coordinate and do the opening and shutting down of a clean room at work. Every day that involves scheduling machines and gas lines for plasma furnaces, photlithographic processing, bookings of metal evaporators and chemical etchers. These have to be monitored as you dont want a furnace starting up near a hydrogen line or someone trying to desposit metals after someone else has been using an oxygen plasma. You stick someone using a piranha solution on a bench next to someone using organic solvents and the explosion takes out a lab. So, we have booking systems and clean room managers monitoring it all.
There are 16 slots a day for a clean room of 20+ people using it on a daily basis. The whole system is done by email and updates around 4-5 times a day. By not sorting slots out people cant do any work which costs money. The raw materials are substrates of silicon carbide (several times the cost of diamond) and sapphire and onto them go layers of precious metals. Days and days of work can go into making these chips and someone contaminating the step or screwing up the schedule can wreck them - the costs for this are far from trivial. This timing/scheduling isnt a special event, its just day to day stuff we do that needs responses within the hour during office hours. Its not that were running google but it is necessary for safety and so people can work - even for us mere mortals.
Were not allowed to take laptops into the clean room as they have fans and are also used outside. Phones are ok in the entrance areas where we get preped. Just going into the entrance room and checking a phone when it beeps is a lot quicker than having to constantly go back and forth to my office, changing out of coveralls, protective overshoes and gloves.
Then theres customers who we dont want to keep waiting and the constantly changing meetings. These are the thinngs that you need to respond to within an hour or so even if not instantly.
Not everyone in the world sits in an office at a desk typing code. If you find yourself at a computer screen for the full day then youre probably not very useful to the company anyway. My bosses hardly ever even get to their offices as they spend the whole time in meetings and at conferences. If they didnt have mobile email then theyd never know what was happening.
