Jay, we don't use the b word in public forums.
I don't think that any dev on the planet reacts to this sort of language, regardless of the problems you may experience with their products.  ;)

Second, you will hardly find more than a few addon planes being able to run multicrew (meaning shared cockpit) without problems. Mainly huge lags are their big concern and you have to develop a complex plane for multicrew from the scratch to run it adequately and stable.
So the afterwards patching to enable it is rarely, if ever, used. At least all the multicrew planes I know came with that feature from the very beginning and all (few) upcoming ones also include that feature from the planning phase on or never.

So demanding from CS to patch their stuff is a bit short-sighted when knowing these facts.
Yes, the FSX standard planes support that feature which was a big advertising thing back then. Since they are not nearly as complex as most of the addon stuff, this can be achieved with far less manpower.
So FSX brings in the feature but the plane has to support it. Looking at my hangar (which includes quite a lot of complex airliner stuff) only one! multicrew concept plane is available and actually works. So this "a lot other devs" statement isn't supported by me, sorry. I know another one, but this thing doesn't even offer a VC, so it looks more like a tradeoff than a solution to your demand.
You can start all the others in multicrew of course, but you won't get them to fly or show correct values then. The gauges are just one part which have to be able to take the load of two pilots while staying synchronized and operative for both.

The GA sector looks a bit better in this aspect but also means that we're a talking about a huge drop in complexity there. But, even with this in mind, most of the stuff fails on multicrew while some are actually able to take it, by concept.

I would recommend to first, lose some of this bad language and second, to look into some developer forums where the "small" problems with complex planes being able to run multicrew are described.
As said, maybe some one or two are coming up in a medium-term cycle and this feature surely is interesting, although it might be the most underestimated feature of FSX and only few people actually use or demand it.


Here are some guys stating the same demand like you do. Looking at their list of supporting planes, I can see my numbers being right. "Few", to say the least.
http://forum.avsim.net/topic/277886-shared-cockpit/