Of course you're allowed an opinion, did anyone say otherwise?
When your opinion is so strong to say something is "terrible" then I think you will find people are interested to how, from your experience they can be so bad.
I hear what you are saying about a tuning box, with proper installation it shouldn't be a problem though. And if the worst happens then five minutes and you can disconnect it and carry on. I know people with installed remaps who have had lots of trouble, and the only going back has been for the tuner to remove the map, not quite so handy.