Let's be honest about this: fansubbing is a form of piracy. It's illegal. The only reason the toku fansubbers haven't been stamped out of existance is because they operate in a territory (i.e. the United States) where the creators of these shows aren't making any money, which means they have less motivation to spend money on taking people to court.
This is from before I got into the fandom, but I remember hearing that Toei once announced that the film 'Kamen Rider The Next' was going to get a North American release, and TV Nihon immediately got a message telling them to take down their fansub of the film or else they'd be issued a cease and desist order. So that's kinda become the unofficial rule: only sub things with no legal release, and if something later does get a legal release you take down your illegal version ASAP.
Also, from what they say it seems most of the people who make toku fansubs are doing it at least partially because they want to promote these shows and get more people to see and enjoy them. But fansubs only reach people who either are already fans or hear about them through word of mouth. A DVD promo campaign from Shout Factory will reach many more more people and create many more toku fans. And of course, if something gets an official sub then the people working for OverTime, TV Nihon etc get to kick back and do something else with their free time (maybe even watch some toku!) instead of spending it working on subs.