you're strangely obsessed with what you call 'replay factor'.
Men of War games, even back when they still had different names (
Soldiers: Heroes of WWII and
Faces of War), have always been about heavily scripted, story-driven singleplayer missions.
Vietnam simply continues that tradition, as will the upcoming
Condemned Heroes.
Assault Squad is the odd one out in the series. it was built with multiplayer in mind, thus its singleplayer is limited to a skirmish mode. you might argue that it offers more replay value, but a lot of fans of the series would say that they'd prefer the more traditional approach to singleplayer instead of what is essentially a multiplayer game type with AI-bots.
MoW: Vietnam focuses on individual unit tactics, as did
Soldiers,
Commandos and
Jagged Alliance. none of these games ever had a skirmish mode, or anything that you'd consider as providing 'replay' value. yet nobody complained about that.
tl;dr: you're requesting a feature that isn't at all common in this type of game, and one that was never advertised. you bought this game knowing it comes with 10 singleplayer (and co-op) campaign missions. why is this suddenly not enough for you?