That's what Laporta did (under his reign we went from 100.000 socis to 180.000 or so?), and Rosell/Bartomeu put a halt on that.It's better to give foreigners who care about the club genuinely membership instead of these lazy socios. But sadly "Catalunya fuck yeah" lobby would be outraged at the suggestion.
From a Barcelona soci point of view, I think it makes sense that they're in favor of restricting the foreign soci-membership. It's already very difficult to get a season-ticket nowadays (I think the waiting-list is 10 year or so), and of course, the more socis, the harder it gets to get a season-ticket.