Personally, I think the biggest annoyance is people who complain and talk about how crappy something is before they've experienced it for themselves. Sure, the experiences other people post are helpful when planning and when evaluating something, but until I use FP+ the way I tour, I have no real way of knowing how it works for ME. I know how it works for this DISer or that DISer, but they're not me.
There are people here who have reported that FP+ worked just fine for them ... there are even fans of the system, who have used it and can't wait to use it again. I get that it's more fun and more human nature to read the negatives as validation and ignore the positives as anomalies, but the sample size here on the DIS is so minutely tiny that I can't imagine someone assuming the things posted here are representative of the system as a whole.
I do agree with someone upthread, though ... while it may seem cliché to say, "Well ... just don't go then!", it really is the only option. It's not like Disney's going to not roll out the rest of FP+. If it's something that someone is opposed to before they've even tried it, then choosing a vacation destination that doesn't have you stressed and angry before you've even left might make for a much better overall vacation experience.