Owning your own wallet.dat and having the bitcoin client running on your own machine is absolutely fine for the technologically inclined, but this methodology is totally at odds with the mainstream.
Normal people have big problems with security on their home PCs, they routinely forget even basic passwords or write them down and stick them on the fridge. Most have trojans of some kind installed, and email phishing scams frequently work because the general public is too dumb to realise when they are being scammed. Having mainstream users look after their own wallet.dat and be completely responsible for the security of it is a recipe for disaster.
In addition to that, the home desktop is becoming a thing of the past. More and more people just have a home laptop, a work desktop, a smartphone and maybe a tablet too where they access the internet, so the idea of a computer which is always on is totally alien to many, let alone one that has to be on so they can access their bitcoins and spend them.
People are getting used to having their Gmail wherever they are, and being able to log into their online banking, Paypal account and so on from any device, regardless of whether there is a particular service running on their home network at that particular moment.
If we are to make Bitcoin a mainstream success, the only way to do so is with web-based or cloud-based wallets (accounts) which users sign in and out of like their Gmail or Paypal accounts. We must have sites like mybitcoin, but ones which are trustworthy and secure.
One setback should not deter us from the goal of simple to use, web based Bitcoin wallets. We must not shy away from learning from the mistakes of others.
No Shit Sherlock.
Your post is totally off-topic.
Problem is in personnel, funding, and insurance for such a project. For starters.
But please go find another thread among the many that are already discussing this, like in Project + Technical Development. If you can code, it is open source. There has been an outstanding 1000 btc bounty for an android bitcoin app for a long time.
OP is talking about something totally different for very advanced users. Keeping an off-computer piece of information that can be used to store bitcoins. Joe six-pack is never, ever going to use this technique, so don't worry about it.