On a semi-serious tangent: I have a few different writing styles. You would (obviously, I hope) never see me use "gonna" or "coulda" in say, reports I used to write at my old job. I took the time to write them out, print them, and red pen them before submitting. Similar, but less stringent checks with emails that were widely distributed or going to other than coworkers with whom I closely collaborated ("Hey, you wanna go to lunch?" is perfectly acceptable to coworkers/friends).
When I write stuff on APS, I write in a style that is similar to how I talk with a group of friends. I consider this a "virtual" neighborhood street corner or garage where the guys (and gals) get together. I wouldn't use "gonna" in a formal talk or presentation, but I certainly use it, and a host of other contractions and slang when informally talking to the guys. Ain't nothin' wrong with that, IMO.