Is there some reason why only 3 versions of C4D are supported via C4DtoA?
C4D is kinda a weird package in that a ton of plugins are licensed to your C4D serial number (which means they need to be re-licensed or even repurchased before you can upgrade). Likewise, the yearly release schedule for MAXON hasn't really been that great of a thing- there's very little reason to upgrade every year unless you've got MSA and you're able to upgrade all your plugins at the same time. Some people also don't upgrade simply because there are no features that they need from the newer versions, and there's no reason to fix what isn't broke.
So a lot of people are stuck on older versions of C4D... Either by necessity, or by choice. R20 is a bit of a big one too because it's going to require a lot of plugins to be recompiled and/or slightly modified to work, which may or may not happen with a lot of plugins for quite some time.
Is there any way SA would either consider:
A) extending support for R17 for another year (just to give us some breathing room, especially with R20 coming out and a lot of plugins requiring time to get up to speed), or
B) open sourcing the C4DtoA plugin as SItoA was on github so that we can maintain our own versions of the C4DtoA plugin?