In my opinion, the inactivity of Rheinland has many reasons, which need to be worked on:
Corporations are left behind
Why should the average player use ALG/Daumann/Kruger/Republican, if they can grab a Zoner Whale and go the high profit Cardamine/Slave route? The average player values the combat RP with fighters/bombers/caps higher then the trader RP. Trading is just some expedient for fighting. I see this attitude as a major reason, why people tend to get money as fast as they can.
If they would accept a little lower profit in exchange for more RP, then the Rheinland companies would get more employees, I guess.
That's why can choose between more profit for the companies, or players, who give RP a higher priority.
Rheinland mentality
I want to give you an example from myself, to clarify this point: I am not capable of acting as a blood-thirsty pirate. I just cannot do it, because my personality isn't capable of it. I can't imagine to be cruel and a bully. That's why I have no character in unlawful factions. (The only semi-lawful is Dean Kadwell, the technology addict Junker, but he isn't a murderer or never-do-well.)
I believe that most of the players in this community are similar: Rheinland RP requires some basic personal properties in my eyes. You do not have them? Well, then go play somewhere else. Just take a look at my beloved RM: We have only a handful of people, who I consider the core of the faction. All of them show outstanding RP, cleverness and adaptability within their role. Don't tell me that you can do that, if you have a character, which has completely different properties.
We need to find those, who suit the role, and not people who want to try out the role and only come up with odd stereotypes.
The RM itself
Well, as much as I like the RM, I see huge problems between their RP mission and the general common sense. Don't get that wrong, I consider us to be fair, respectful and we show common sense if we are treated equally.
I am referring to the traders and the embargo. We have very strict rules, and we even plan to make them more restrictive. Why? Because it is the role that we play. I personally would like to see more traders come in and adapt to our RP, trying to deal with us. But the only traders I see, are ZBT slavers or people who don't understand us at all. Where are the supporters of Rheinland outside? Who risks his life for supporting us with needed resources, like Platinum? All people bring in Neon and other stuff, which brings high profits... heck. Look at my first mentioned point. Rheinland rises and falls with the value of RP YOU give to it.