The GTI has become the niche car because leasegate initially made the R very accessible, the better car became the cheap option.
With access to cheap leases gone and the GTI getting a £1250 deposit contribution that no other performance Golf got, the gap was big enough to make the GTI cheap enough to justify the HP difference and no Haldex.
Then VW has recently closed that gap again by making previous options a compulsory purchase and upping the RRP to close the gap between the GTI and the R, and then making the £1250 deposit contribution available to it.
I'm not criticising the GTI as a car, i'm criticising the cost of it vs the R. The RRP price gap/3 year ownership cost gap is so low between them that most would pick the R over the GTI. When you can get an extra 36% HP and 4WD to put it all down, for 8% more monthly cost, it doesn't add up to most people.
All the above is VW's fault. Extra equipment for nothing is welcome, but when they cause a hike in the RRP on what is an already expensive car (relative to its peers), I think they've shot themselves in the foot if they want the GTI to remain "the" VW hot hatch. That Haldex is worth £1500 (around what it costs to option Quattro on certain A3s), and the drivetrain differences add up too.
If I had decided that 220ps was fine for me, i'd expect the GTI to be a solid £4k cheaper and £100pm cheaper if PCPing.
You can get standard GTI PP performance and GTD mpg by adding a DTUK box or remap to a GTD and making sure you don't have BS on the front wheels, and not have any real reliability anxieties. You can do the same to your GTI to get it up to R output, but it won't have 4WD and i'd be a bit worried about my clutch and turbo.
Next to the R, the GTI looks too expensive and the mpg savings against the R are piffling next to a boxed/mapped GTD.
There's no snobbery here on my part, I bought the R because I was sick of frequent tramping on my GTD, and the GTI wouldn't have cured that. I was quite happy with the output of my DTUK'd GTD and the mpg. As luck would have it, due to the collapse in the price of oil, my fuelling pence per mile costs are the same in the R that it was in the GTD when diesel was at the lofty heights of £1.38/L.