But, they're meant to be played in release order. That's why they keep including cross references, easter eggs and such for the people that played the previous games, not to mention they retcon/expand on some stuff that would make less sense if played chronologically.
If they wanted you to play MGS3 first they'd have called it MGS1.
What? Look man i played my first run through the exact way i listed (exception to peace walker not being out yet) and it made a hell of allot of sense then jumping back and forth between eras. the easter eggs and references still made sense just later on. this game series is already complicated as it is its at least better to understand where the story began then to jump half way into it and then going backwards.
explain on your retcon/expanded stuff? if your talking about that encyclopedia thats on the PS3 theres waaaay too many holes in that thing to make it canon! fans have already agreed that until konami gets off their ass and fixes it, the Metal Gear Solid 4 Database remains non-canon.