I also agree with the posters who said that we, as Disney guests, just have to adjust our expectations. OP, I am sorry you left feeling frustrated. I know that I have certainly been in situations before where I felt frustrated with a change - it can really feel defeating. However, I have learned to adopt an "it is what it is" motto - and, no matter how any of us feel about FP+, it is what it is. So, we either have to adjust to the new system, or choose to not go. I think either option is fine - some will adjust and continue to go, and others will find it less enjoyable and no longer go. Everyone has to do what works for their family.
OP - I think the advice here is great. Adjust your expectations to doing less each day, let DH go by himself early is he wants, stay onsite to let you get FP+ earlier, etc.
That said, I am amazed at some of the negative comments on this post - those directed at OP and those not directed at OP. OP is entitled to feel that way OP feels without being attacked. Similarly, the person who mentioned their family doesn't yell was attacked for pointing out that screaming is not a result of FP+ - FP+ doesn't force anyone to scream. Some people just handle stress in different ways - I used to be a screamer, so I totally get where the OP and the commenter are coming from. However, I tend to agree with the commenter in general - that screaming can't be blamed on something that happened in the vacation. It's all about how you handle situations - otherwise every person would react the exact same way to the same situations.
I think part of the problem was that the title of this post is going to ignite a response in everyone - people who hate FP+ were going to agree, please who like FP+ were going to disagree. Saying a reservation system "ruined" your vacation and saying that a reservation system caused screaming is probably not accurate, though it may feel that way. Likely, OP feels frustrated because, like many of us our first time, the FP+ system did not yield the results she was hoping for, which put her family in a stressful situation filled with disappointment, which they reacted to negatively (no judgment - I react negatively in situations too).