The are different levels of "community" when comes to classifying players.
I would say that just buying the game does not make you apart of the community. It certainly makes you a fan of the game if you enjoy playing it as much as anyone else does, but lots of people have bought this game and really can't be considered a fan or a member of the community. For there to be a community, there needs to be active participation with others on some level for it to exist by spirit of definition.
If you bought the game and play solo mode exclusively, but participate on the fourms and in discussions, then I'd say you are a part of a community. The question is, which level of community are you apart of? I've played many games that have members that could be said to be apart of the community, but they dont actually play the game and only participate in discussions of the community forums.
When it comes to game play elements, we should focus on the segment of the community involved with playing the game. Since "Community Goal" implies (to me anyways) a goal to be accomplished by players together, then it should be directed to the portion of the community that is playing the game together. As a player in Solo-Mode, you are still a member of the community, but you are not participating with your community in playing the game together. You are in fact, deliberately isolating yourself from the communal portion of the greater community.
That's not to say that I think that players in Solo Mode should not be acknowledged for playing the game on some level, but maybe the game needs to separate and make distinctions between where contributions to a community goal are coming from.
One recent Galnet post about the progress of an on-going community goal signled out a CMDR for having destroyed 14,000 enemy units. Is such a thing even possible outside of farming NPC's in solo mode? That's a ship destroyed every 6 minutes constantly for 90 days straight. Is that an accomplishment worth distinguisging over a CMDR would defeated 140 unique players in 1v1 combat while exclusively in Open mode? How do you weigh each contribution and merit within the context of a community goal? If the game isn't going to make the distinction, and the gameplay ultimately revolves around earning as much reward as possible from "Community Goals", we all may as well just ignore open mode play and farm criteria from solo mode since it is apparently far more statistically efficient to do so.
I really don't think the game should revolve around a static number on a database spreadsheet hosted by the server. It's not about amassing 1,000,000 tons of cargo in X number of hours, but what stories come from the attempt at everyone trying to contribute to that total with in the limited time period. It's ultimately about the story. Your story. My Story. Our Story most of all. What other point could a "Community Goal" have if not to get the community playing the game together regardless of the criteria on someones spreadsheet? If everyone forgets that and focuses strictly on the static criteria, which I think Solo mode can be exploited for, we are ultimately missing the entire point of being a community playing Elite Dangerous together.