Sorry, but if you want to run Bitcoin-QT on a local machine, it will be easily able to handle the few GB (current computer games are MUCH larger) of space and traffic. Otherwise you can also use prominently featured lighter clients like Electrum or Multibit.
Please tell me exactly why me reasoning that having a block chain that contains 4 years(!) of binary transaction data and still is half the size of a current computer game (random google, yes I know it's XBox One...:
http://callofduty.digitalwarfare247.com/2013/11/call-of-duty-ghosts-is-a-39gb-install-on-xbox-one/) is "arrogant and narrow minded"?!
Currently the block size limit is ~1 MB, which gives a constant hard cap of about 55-60 GB of transaction data per year. This can be stored on a USB drive that you can get for 30 USD with free shipping (again random google, I am sure you can get it cheaper too:
http://www.amazon.com/SanDisk-Cruzer-Flash-Drive-SDCZ36-064G-AFFP/dp/B007JR5304).
How the hell is this amount of storage going to drive away "most of the average people"?
i've worked with average people (as in not technically skilled about computers) for decades at local university so i got to know how they think and the limits of their understanding (as in interest in learning something they don't have to/want't to or need to).
anyway, a game which they will delete after a few weeks and replace with another. not so for the blockchain
you really don't see the problem with such a huge amount of space required? how long do you think it will take to sync a 100gig blockchain. weeks? what about 1tera, a month?
so first time user will have to wait way LONGER than a bank wire transfer. so much for the "transaction speed".
so on one hand you have the idea of decentralization, and on the other ease of the use and efficiency. what is the middleground? some form of distributed blockchain?