Since the title is "Why buy a GoPro" and you don't want to buy one, don't buy one. I have used the Hero2 and now i have 2 Hero3 Blacks and I will always buy them but I have used the midland, contour, and a Sony action cam and all did the job for far less money.
I prefer the GoPro because of all the different quality settings. I shoot mostly in 1440p and I get great image stabilization when I use my software because its well over sampled. I also like picking my field of view. The fact that it will shoot up to "4K" is neat even though its only 15p but the 2.7k is 30p. GoPro also has every accessory known to man and third party makes a lot of them too. The app is superior to all the others. GoPro is leading the way now and because of all the money they make, they are only going to get better in the future.
2007 ZX-6R: MotoGP Replica fairings, Yoshimura RS5 slip on, PCIII, Black CRG Click & Roll levers, A1A Bar ends and Grips.