If the cost of running a full node is so cheap and so fast, SPVs wouldn't even be needed; this removes the need for many things such as the inefficient (and not working) Bloom filters. The thing that stops individuals from running full nodes is how long it takes for the initial synchronization process.
Not necessarily. It's worth considering that not everyone has a PC or similar device they can dedicate to the task. I know plenty of people where they just own a tablet or netbook that wouldn't really be suitable and then other things like smartphones and gaming consoles, which aren't of much use in running a full node either. The idea of everyone having a "home computer" has been somewhat diluted as of late. People seem to prefer their portable devices now. Because of this, SPV is always going to be a significant proportion of the userbase.