I agree with those mentioning the documentation. It's by far the worst docs I've ever read for a commercially available 3D DCC software. (I've read many over the years).
2-6+ year old pages are the norm it seems. As well as entirely missing chapters. Many new features have no explanation at all, leaving users to guess at their functionality. A chronic lack of screenshots (especially in the guides sections) to help, you know, guide the novice. And where there are screenshots they are old and outdated. Formatting is inconsistent and the labeling/naming has discrepancies between the App and the Wiki (and I'm not just talking about Colour vs. Color). Node reference tabs split up across multiple pages (why?!). And overall, it feels like it is written by programmers, rather than by (tech)-artists for artists. Too dry and in many cases needlessly repetitive. I could go on....
If you want to grow your user base, you absolutely have to start taking this seriously. It's been bad for as long as I can remember and it is partly to blame for TG's reputation out there in the VFX & games industry (awesome quality, but too much of a hassle/difficult to invest time to learn it). Terragen is a tough cookie to crack in and of itself but the Wiki is the bouncer that chases off many brave souls.
As many new/improved things as I would like to see in TG, instead I'd say hire one less programmer and pay for a good tech writer. Don't just rely on "donations" from your user base. That's something that needs to be in addition to a solid documentation, and not serve as the band-aid.
Sorry if this sounds a bit harsh, but I've spent the last few days reading through the Wiki and it gives me the same painful flashbacks from when I last read it........ back in 2011!