All that the bots do to the game is they accelerate what will happen to the economy anyway.
Right now mediocre but effective gear is not out of reach for most players. If there were no bots then maybe that same gear would be more expensive, but over time the prices would still fall. Personally I enjoy having greater access to better gear. Really godly gear will always be so rare that it will hold its value regardless of the bots. I realize that you can get to a point where upgrades are out of reach due to extremely high costs of top gear, but that would be the case with or without bots.
I agree that bots accelerate what would already happen by itself anyway (in the long term anyway), but that doesn't mean it's fair to the players who didn't bot it originally. There is immense wealth to be gained and transferred through the use of a bot, especially when it was not quite as wide-spread. You may benefit from the cheaper items in the long-term from bots, but you will not have anywhere near the same wealth as they do.
I agree with you , bots do give an unfair advantage. You cant compete with people who cheat unless you are also cheating. Why do you feel the need to compete with them? You want the #1 barb or whatever on diabloprogress or something? If thats your goal then why not just break out some real $? At least you arent cheating that way lol