Most of the replies center around cost which is a factor but if you're into driving then price becomes secondary. Coming from a stage 2 Sti, the RS is a nice upgrade and really out handles a stock STI.
The STI and RS are substancially more car than a front wheel drive ST, even when the ST has been modded. The AWD setups and power delivery are impressive...oh, and did I mention the cornering?
Like everything in life in boils down to priorities, funds, preferences and availability.
Cost isn't everything, but for the price there are a few direct competitors and a few non traditional ones, as well as a myriad of other cars coming into reach if one were to take the mark up into consideration.
I wanted one badly enough to go through the process of trying to find one, the one I saw had been sold, and I was told I could order a 2017 at MSRP, but I ended up not going forward with that plan, not because the price was necessarily going to be too expensive, but because at the time I was not certain if some time after I ordered the car that I would regret the purchase without at least considering the alternatives.
I would have really needed to drive one before committing to spending the money, which is a real problem for something that has only been delivered 1674 times this year through September, or about 1 per every 5 focus STs sold in the same time period, and the limited stocks available at dealers within 100 miles or so of where I live.
I won't say it is not worth the money at the sticker price, or if you're really in love and can afford the mark up, but personally I couldn't do it at this time.
Yes the AWD is amazing and technically advanced compared to other FWD based systems on the market (cough, haldex, cough), and it's blisteringly quick around VIR being over a second faster than a Mustang GT Performance Package car tested the previous year (1.3 seconds).
Ford Focus RS at Lightning Lap 2016 ? Feature ? Car and Driver
But with the wrong tires it can be bad on our poor roads, if I lived somewhere where the roads are good, the weather temperate, and I had significantly deeper pockets to the point where I could have a complete fleet of vehicles (not just 1-3 as now), I'd have added an RS to my collection of a daily driver/winter beater, summer daily and nice day options.
However, once you transition to Michigan’s far-from-perfect public roads, housebreaking the RS proves to be the frustrating stuff of a ride-and-handling engineer’s worst dreams. This RS vibrates like a paint shaker on two-lane roads; it borders on unlivable when respecting posted speed limits. Crank up the velocity to criminal levels, and the RS actually settles down a bit. The ride evens out and the steering stops favoring the road’s topographical features and starts to better hew to the driver’s desires. But it’s a lot to ask of a driver—say, his or her license—when a good car is at its best only when doubling the speed limit. The dampers are adjustable, but the stiffer of the two settings is seriously overdamped for public roads. This track weapon never feels settled, and neither do its white-knuckled passengers. Going with the base tire won’t fix the brutal ride on rough roads, but it will quell some of the tramlining.
2016 Ford Focus RS Tested with Michelin Pilot Sport Cup 2 Tires ? Review ? Car and Driver
So on balance I'll let someone else have the one I was going to order and went for the Mustang GT, not because it's necessarily a faster car, or if it was less expensive (the one tested by Car and Driver for the Lightning lap in 2015 certainly wasn't much cheaper than a loaded RS), but because of the feeling I had while driving the car.
I'm sure I would have enjoyed the RS quite a lot as well, but I'd have wanted to put 18" wheels on it with bigger side walls than the standard tires to give the car a fighting chance of surviving on our bombed out roads.
I do fully understand where the money went and it was into the engine and drive line as well as the chassis modifications to stiffen the body shell.