Really, I do.
Galleys are that penultimate step (on the author's side of things) to publication. The story's done, the layout's finished, the book is pretty much ready to publish. Not much left to do except go through the galleys page after page, line after line, word after tedious word.
This is soo not the time to be making changes to your story, or even the sentences. All you really do with a galley is make sure everything's spelled correctly and there aren't any stupid grammar mistakes.
This is not the correction of your work, for by now you will have long turned in a clean copy of your ms and your copyeditor will have made it cleaner. No, this is the time for the correction of any slips-of-the-wrist that may have happened during layout--not the author's fault (in theory).
Nobody's perfect, not even the book designers. (Really, we love our book designers.) But once in a while something will happen: a reversal of two letters, a missing or present apostrophe, a dropped word.
These are what we try to catch in the final galley proofs.
Now, the problem with the human brain is that it's got this auto-correct feature. It can see part of a pattern and fill in what's missing, often without you realising it.
You know your story, you know your words. Is something missing? That's okay. Your brain will fill it in for you.
And thus you might miss a tpyo in the galleys.
To keep this from happening, one must slow down their reading speed. And then one must read backwards. One must get a ruler or a piece of paper and go line by line. Only by making the brain work hard, can one find these little errors. (Now that I think about it, I can't think of many galleys I've gone through that didn't result in an errata sheet.)
Because of this reduced reading speed, the going through of galleys becomes a painfully slow and tedious job.
And that's why I hate galleys.
That said, I would not do away with this very important step of going through galleys. Just think how much more I'd hate it if I never got the chance to catch some stupid little mistake.