One thing that occurred to me while doing the first mission was this: How will the game come across when a new player sees these cool cut scenes on these missions, since they are relatively early missions, and most of the other missions are blah in comparison? The first impression it would give me is, "Oh, they didn't feel it necessary to put as much effort into all of their missions." All current players know the history of the remastered missions but a fresh player won't have that knowledge.
Agreed. The remastered missions make leveling interesting; I don't think the non remastered ones would make your Silvers sub. Remastering all of those missions is a lot of work though.. so I dunno how Cryptic would go about doing it.