What concerns me most I guess is that while opinions are mixed on FP+, almost everyone is experiencing higher crowds and longer lines. Is this just a recent trend in the past 2 years? Why? (Guess it doesn't matter). I am trying to figure out why FP+ would cause more crowds and more lines but don't understand it.
Yep, attendance has been up every quarter since I've been following -- the last 2 years or so. It feels packed, even on what might reported as moderate days. I can't imagine July... Hotter and ever more crowded?

Then you've got the crowd that used to take full advantage of FP- to pretty much never wait in a line. To this crowd, the fact that they now can only do this 3 times, makes the lines seem longer because they're having to wait in lines they never did before. This is where most of the long lines angst comes from. FP+ does not cause more crowds in itself, but if you used to not wait for anything, and now you have to wait for some things, that's going seen as longer lines. On top of it you've got the rest of the guests who pretty much never used the old system, and these guests are now each getting 3 Fast Passes, so the ex-pros have to wait for the average guest to get their rides too.
"we did WAY WAY more than 3 headliners per day with less than 15 minute waits."
Ditto... and you should, now. I might nix the two "WAY's" tho.

You'll do more than 3, but not 12. Especially if you do rope drop. Even the most put off of guests would agree that 3-and-done was more of a vent and not the case in practice. At the MK, you can pull FPs well into the afternoon. At the AK, nobody is really complaining about the waits, since the 3 FP+ you get covers the cool rides there. At Epcot and DHS, it's good to combine rope drop or late nights if you want to ride a lot of Soarin, TT, Toy Story or Rockin. I'd expect these to be 60-90 most of the day, especially in July. These rides are overly-popular not so much because of the ride, but more there's only 2 primo rides at each park. So, the FP+'s to them go fast, and guests are limited to 1 per day due to simple capacity.
"If I am supposed to be happy about 3 guaranteed FPs, I'm not, not at all."
How did you fare before? If you were in the group of folks who pulled lots of Fast Passes in the past, and you expect to be able to do that now, you can't. You get your 3. Everyone gets the same, and it's difficult to pull any more than the next guy.

On the other hand, the 3 you pull are pulled more efficiently than before. Like if you would have gotten an 11am, then a 7pm return time, now you can line them up... 11-12-1... and pick them around where you'll be dining, and not be stuck waiting for that 7pm one, or having to come back to it later.
"I am a planner by nature and I KNOW that it will make our park days more enjoyable"
If you like to plan, it is great! You can organize your mornings in more efficient ways. Pick your return times, line up your rides back to back, squeeze in a B-ride in between them, or whatever you want to do. For this and other reasons, I happen to like it. I make a spreadsheet, and my family thinks I'm crazy for doing so.

If I could pull a FP+ to both Toy Story and Rockin in the same day, I'd say FP+ is awesome. But since you can't, I like it but wouldn't go that far.