I think some of you may be confusing linear with what you're referring to as "Metroidvania" (for those not understanding, cross between Metroid and Castlevania SOTN style) which allowed you to explore multiple areas from the beginning but you really couldn't progress unless you had certain key items. RE0, RE1, RE2, RE3, RECV, REOB, REOBFile2, and REDA all sort of had this style. You could explore some areas which would be open but you couldn't get to much further unless you had certain items. To a degree, RE4 allowed this but it wasn't as open as the earlier games. RE5 really didn't have any exploration and you couldn't even get to another area unless your partner was with you. I don't know if RE6 is going to bring some of this style back or not but it is what it is.