It hardly challenges the drivers! It's not like it makes the car hard to drive on the limit or anything. Like I say, it's not relevant to road use and it doesn't make the sport any more enjoyable to watch.
It's an utterly brilliant technical innovation that's made testing far more interesting from a technical stand point, but there's zero benefit to keeping it in the sport long term.
Things like CVT gearboxes had a long term relevance and are used everyday now outside of the sport, so that's an example of a technical innovation which could and maybe should have had a long-term future, but things like fan cars, active suspension, F-ducts or exhaust blown diffusers don't. As brilliant as they were and relatively simple in the F-ducts case, in my opinion it was right that were ultimately banned as they added nothing other than spreading the field out.
I've got magnetorheological semi active suspension on my road car, so why can they not have that on the pinnacle of motor sport ?