You change the size of a wing and all aero needs to change. If rule changes arenade on front wing, this affects air flow over the entire car, they have money to do aero, what teams say is they don't have money to do big new engineering like. Kers which is something totally different.
The reason slip stream looks less is because after final corner they are much further back therefore they only start getting into real slip stream towards the end of. The straight and it's folate. When they could follow nose to bumper this didn't happen, DRS doesn't solve this at all.
You have aero which doesn't creat dirty air, which they are doing. Ground effect,you could even bring skirts back. You then reduce the size of front and rear wings, and get rid of all bolt on tat (on the wings) and only have one board. You then get stickier tyres and you bring back bigger bhp. This will do more than solve dirty air and you would get great racing again. Its also cheap ground. Effect is cheap and much stricter aero means less design options. But IMO you needy open up and engine and kers design otherwise there is no inventions.
The slip stream is still there, what you don't have is differences in break horsepower like they use to have, it is not just dirty air.
It's a cheap option but doesn't solve the problem and is a cheat and completely stupid. DRS is nothing like previuse seasons even going back to 70s.