VPN really is for security, and was originally focused on Corporate Companies and remote Workers use, if your using Web based VPN Services you can have the added bonus of being Geographic independent and or changing your IP meaning you can appear to be somewhere you not, as well as benefits to Security when Coffee Shop Browsing.
Onspeed where one of the original players which was launched to Accelerate Internet Speed (predominantly Dial Up) by using Data Compression, but become very popular with Ex Pats wanting to watch BBC iPlayer outside of the UK. Then you have the Speed Throttling or Downloading Bars, ie, Torrents, Adult, Media Downloads etc which started big in the States by ISP and Mobile Networks.
As for Big Brother, Im sure they have the means or powers to listen in or track anyway.
If your mainly at home, and dont spend half your life on other peoples Coffee Shop, Hotels, Airports Hotspots, then just use your own Secure Network or Home VPN rather than pay some monthly fee to a Third Party who may or may not be in the business of securing your information anyway.