there is the message is pretty simple everyone is building apps on top of facebooks data. Basically all these startups are just facebook with a twist, if you really want to make something good that has a chance to disrupt as much as facebook and twitter did you should start from scratch and invent a new category.
If you wrote an email to a VC without being able to demonstrate that you picked up basic writing skills in high school and college, you'd have a longer road to travel to convince them of your overall fitness for funding.