I have to disagree, but some may say I am a bit biased.
Once a car is running right, there's no need to adjust anything. Some people just like to have it to play around with idle and stuff, but in reality you don't really have to change anything once the car is programmed right.
On top of that, I would guess that 90% of people that own tuners don't really understand how to write a file. And if you don't really understand how it works, going in and messing with spark and fuel could be a diasaster. Don't get me wrong, the EEC tuner is perfectly suited for some people.
We have a simple process to get your car running right. After you buy a chip, we recommend that you take the car to your local dyno and do a few pull with a/f. If you send that info back to us, we will reburn your chip once for free to adjust your car for the ideal ratio. That way it's still cheaper than an EEC-Tuner, and your programming is done by a professional.