I think they thought it through very well.
The end result of FP+ is that people who are willing and able to commit to WDW in advance by buying park tickets, and better yet staying at a WDW resort, get the first crack at FPs. Also, some of the other parameters of the system ensure that FPs will be distributed more evenly among all park visitors than they were under the FP system. I think these are both results that Disney intended.
When reading the bad reviews, it's a good idea to pay attention to exactly what it is that someone doesn't like about it. Frequently, those complaints are coming from people who had learned how to take maximum advantage of the paper FP system and are understandably not happy that the FP+ system makes it virtually impossible for them to get 3 or 4 FPs in a day for something like Test Track, Soarin, or Toy Story. I think Disney knew full well that this would be one of the results of FP+, including the dissatisfaction from that one small slice of its customer base.
Of course, there are other things that some people don't like about FP+. But, there are also a lot of things that a lot of people like about it. When you start with the understanding that you can't please everyone, I suspect that Disney is getting the results it expected, and is happy with them.
On your original question, if you make your FP reservations as soon as you can, or even same day, you will still get something. And, by arriving at the parks early and following an efficient plan, you can still do as much as the onsite guest who got their FPs 60 days in advance. You might just have to do things in a different order.