It's not easy being a referee. So many rules to remember; so much happening all over a very large playing field; players more or less constantly holding, handling, pushing, shoving, tackling, diving, and especially complaining; and just two assistants running the sidelines to help manage the match. Given the scale and importance of the job they have to do, it's no wonder referees make mistakes from time to time. But the rate and importance of referee error seem to be increasing. In fact, the overall level of officiating appears very poor. My evidence is only anecdotal, but I watch a lot of Premier League matches (five or six matches a week on average) and I witness appallingly bad decisions - decisions that actually or potentially affect outcomes - in nearly every match. The model of a single referee with assistants on either sideline is simply not good enough for the modern, very fast, game.
What is to be done? Well, perhaps the FA could follow the National Hockey League's example and put a second referee on the pitch, each with responsibility for half the field. In addition to improving the positioning of the refs, it would provide another set of eyes (on the field, rather than the side) to help with crucial decisions, including bad tackles, penalties, dives, etc.
Putting another ref on the field would not solve all the problems - there is no perfectly functioning rule-enforcement system either on the playing field or in the courts of law - but substantial marginal improvements are available and are urgently needed to protect the integrity of the game.