In Shadowrun, our group had an expression for the combat monster that could do nothing except fight: "the troll in the van".
If a GM in BC chooses to go with the rule book that CSMs are immediately recognizable and unable to disguise their origins, it pretty much leaves all CSMs as nothing more then trolls hiding in the van until their "special" skill set is required.
Obviously, this depends a lot on what kind of game you're running. If its action heavy, in neutral or chaos territory, it will rarely be a problem. But if there is going to be any roleplaying involved, it can quickly get tedious for the CSMs. Some might say that's the price you pay for playing a combat monster, but I don't think that's entirely fair. The game includes 8 archetypes, and while there is no doubt that the Apostate is the "face", 50% of the available archetypes shouldn't be forced into hiding in a cave or convenient vehicle anytime interactions with civilians occur.
Every GM decides how he wants to run his game, but I do think its a weakness and another hindrance to mixed group play. It may be in accordance with the setting, but it still acts as a restriction to roleplaying...something I am not a fan of. It works fine in DW because all play marines, but there is still enough interaction both among the battle brothers and with civilians that it works out. In BC its just another block for mixed group play, in my opinion.
Currently, our RT group is still going strong so we're only adapting the combat updates, along with the modified talents and skills. But if we ever do start up a BC campaign the way I hope, I doubt I will be too harsh on any players wanting to be CSMs. Oh, they'll never be liars extra-ordinaire or firebrand orators able to whip up a crowd, but they will be able to stand around looking hulking and mean without it immediately raising suspicions.