Some people take the banter to heart (and the GTDers took a lot of stick early days), but there aren't many people out there looking for a nasty argument, just a debate. People here jumping ship to the R from both the GTI and the GTD aren't in a tiny minority, so it's a popular theme, and all three of the performance Golfs share a lot of DNA, it isn't exactly VW vs BMW here.
The popularity of the R can't be ignored, for those that won't be keeping their car forever and just look into what their car will cost them over 2/3/5 years are seeing that monthly basis, the R is a massive bargain due to the residuals which more than cancel out the higher RRP vs the GTI. Some here say the PP is so much better than the standard GTI and it's a no brainer to have it, pretty similar circumstance comparing PP to GTI as R to PP or GTI.
Choosing a GTD over a GTI or R can make a lot of sense to people, depending on their circumstances. Far better mpg, lower tax implications and significant (but not huge) residual differences add up to significant monthly savings.
Compare the R to a GTI though and you have minimal mpg differences, more stability/traction from the Haldex and more power as well as residuals so good that they can soak up the extra cost of the car and extra fuel costs for the average miler. Picking an R over a GTI pretty much has no financial penalty to the private buyer/leaser.
Some people will always want the GTI over the R for various reasons, but i'd take a punt that if they hadn't already bought their GTI and lined the 2 up next to each other to make a purchase, most would be getting the R, and there's nothing wrong with that.
This place is far friendlier than rforum at the outset and ongoing (most there do seem to calm down a bit once they get to know you), maybe we've had more time to get to know each other. It's a good thing that the people who have or will soon have an R are staying with this forum for their primary car forum needs because it's a nicer place to be.