Aww Rinenud, I actually hoped you'd give me more time to come up with the ultimate sarcastic retort.
So now instead of making a funny for everyone to enjoy, I need to make a completely boring response (say "thanks" to Rinenud, guys...). So.
Yes, my dear fellow poster. We do have rules for informal discourse. In fact, these very rules allow us to communicate in here, seeing as this is in fact an informal discourse as well *swoon*
Also, in the world you do not typically hear "I have got to go", but /aivgotegeu/ (e is supposed to be schwa). You get my drift? We do not speak with letters, but with sounds. And "I've gotta go" is a representation of these sounds. So if you hear someone say "I gotta go" (/aigotegeu/), you do correct him to "I've gotta go" (/aivgotegeu/), naturally.
And only robot would say /aihavgottugeu/, geez.