Welcome to these threads with your first post! Your comments have been discussed many times before. I'll try to summarize why FP+ is disliked so much:
As an experienced WDW vacationer, let's look at FP+ from your perspective. Today, experienced WDW visitors often can get a dozen FP selections per day at multiple parks. With FP+, you will be limited to 3 FP+ selections per day and only at one park.
With FP, every WDW guest has an equal opportunity to get FP. It all depends on how much effort you want to put into it. With FP+, onsite guests will be at an advantage since they will be able to book their FP+ experiences at 60 days from arrival + 10 days. Once FP+ is well understood, it's highly likely offsite guests will be unable to obtain any FP+ selections for high-demand/low-capacity attractions such as Soarin' and TSM.
Most people are not uber planners and don't want to map out every single moment of their vacations two months before they arrive yet, if they don't, there's a strong possibility that all the "good" FP+ selections will be gone.
The entire NextGen initiative, including FP+, has cost over $2B. Universal built the entire Wizzarding World of Harry Potter for $265M and it now generally is considered the best executed "land" in all Orlando. Imagine what WDW could have done with $2B if they had actually spent it wisely by adding and improving attractions at the parks!
Ultimately, WDW suffers from a capacity problem that FP+ does nothing to address.
The Walt Disney Company CFO Jay Rasulo bluntly summarized for Wall Street why FP+ is being implemented: "So if we can get people to plan their vacation before they leave home, we know that we get more time with them. We get a bigger share of their wallet."
FP+ has little to do with improving guest experience. FP+ is all about more money for corporate Disney.
Hopefully, it's a little bit clearer why we "grumble" over FP+