It's strange that people post prophesies of doom, about how solo/group/open modes and mode switching will ruin the game... It seems that for many people, presumably from all the modes, 1.2 has given the game a positive boost, and I think it's fair to say that the game has not seemed in danger of collapse since December last year, and FD have consistently maintained that they are looking to the future with both free and paid for updates and expansions.
It's also clear that some people would love to see an open galaxy of convoys of traders, supported by fighters for hire, dodging or fighting off pirates, of blockades and space battles on an epic scale, affecting the Universe we all fly around in, and while those ideas do sound as though they might be fun, the technical limitations of the game (instancing with the ability to see only a limited amount of other real CMDR's), not to mention the fact that not everybody plays the game to the same schedule or at the same time, means that these things are never going to work for everybody all the time. If that were the model however, someone who enjoys playing the game when they have the time would be at a huge disadvantage when they log in to trade for a couple of hours on their own, being targeted by hardcore online gamers, and probably the game would rapidly lose it's appeal for them. The flexibility of being able to switch between the modes however, offers this gamer the chance to join in with the open Galaxy when circumstances are right for them, perhaps when they do have friends who are online at the same time, thus enriching open mode at least some of the time, something that locking them into a single mode might very well prevent.
I don't think there's a right or wrong in this (very protracted) discussion, just people's preferences as to how they want to use their own leisure time. Honestly, I think that the influence a single player has on the environment is tiny, probably nowhere near enough to break a blockade by trading solo, and in any case, the outcome of events is not truly dynamic, FD choose whether a blockade has worked, or if a faction has influenced a system to a critical level, and since they can distinguish between solo and open players, perhaps they already take that into account.