Well strangely the mk6 has gone under the radar, and it alongside the mk7 is my favourite gti since early 1992. When i first saw a mk6, i thought, yes. To me the mk5 was almost right but is rapidly looking dated now, the mk4 wasn't a gti, the mk3 went into battle with damp powder but with a bit more spice can stand up for itself. But the best (at the time) modern (not retro) gti didn't get noticed, then it was replaced with the mk7 which did get noticed.
Its not very often i see a mk6 GTI or R (rare). Mk7s gtis are out there and Rs ar relatively common.
I suppose everyone who bought a gti in the 80s now buys a gtd, less enthusiasm for those, more gtd=less gti means less of a community.