You've not read the proposed changes have you? Both wings will be wider, deeper and have the same or more complexity, and the diffuser is getting longer, wider and taller. The exclusion zone that removed the complex barge boards and sidepod wingles, flip ups and other appendages is also being removed.
All the changes they made in 2009 are being reversed. Mechanical grip increases will be negated by the increased turbulence and reliance on aero making it even more impossible to follow closely.
The barge boards aren't really about downforce but airflow conditioning... they will help the car condition the air going over the body and into the diffuser... this will increase the ability to extract downforce in dirty air, not reduce it.
The wings being wider reduces complexity. The massive majority of all the complexity in the front wing is there precisely because narrower wing means they have to work harder to get the air to go around the tire. With a wider wing that extends to the edge of the tire the wing will have to work far less hard to push the air past the tire. On top of that the rules specifically state less complexity in the end plate.
Wider diffuser, wider wings means more reliable and easy to apply downforce, again dirty air should have a smaller effect.
Wider tires = more mechanical grip. One of the biggest problems right now is not following in corners but regardless of the car you will see the lead car get better traction out of a corner, wider tires will help make traction out of corners easier.
Two more key factors people overlook entirely. One is that we see plenty of overtakes by cars following. Hamilton didn't lose performance following Vettel closely a week after Rosberg whined publicly and loudly about not trying to pass Hamilton because it's too hard to follow.
Barcelona is simply a bad track for overtaking regardless, at other tracks Hamilton had no problem overtaking and neither did loads of other cars. Those who complain loudest about following being a problem are making excuses. Making an excuse doesn't mean the problem is actually as bad as they make out.
Another factor people simply ignore is drag... we have cars with 5, 10, 20 or 30 years more experience and knowledge being made compared to however far in the past. People used to stick a massive wing on and get loads of downforce WITH loads of drag. so the lead car was banging down the straight with heavy drag and a huge disadvantage compared to the guy slipstreaming. The cars being better designed with less drag means the lead car has less drag and less disadvantage than they did in the past.
Merc struggles to pass the williams on a straight because it's a low drag design more than because the Merc struggles for grip. 10 years ago Williams would probably lose an extra 10-20kph from drag and the car behind would have a greater slipstream effect also(because reduction in drag would be higher in that era).
It's not purely a following car issue, 10 years ago the car behind might lose 20kph due to drag and the car behind might gain 15kph to slipstreaming. Today the car ahead loses 10kph due to drag and the car behind only gains 5kph due to slipstreaming.
Cars are better and more advanced than they used to be, this will ALWAYS be true now. 30 years ago you didn't have guys doing fluid dynamics/aero degrees being taught by aero guys with 30 years experience in the industry... today you do. Regardless of the rule set the cars and knowledge will never go back to any particular golden era.
Fans knowledge of what is going on is also a problem, they all think they know both what the rules mean and how to fix it and by and for the most part neither are true. Despite the rules dictating less complexity in the end plate and despite the narrowness of the wings being the primary cause of the current complexity you believe the new rules mean more complex front wings.......
