I might point out that Raven Shield was PC only. The consoles got "Rainbow Six 3" instead, and it was a rather different game, delivered significantly later after its own extended development cycle.
I know you should wait until a game is released to bash it, but it's really hard when they release videos like the R6:4 trailer.
I'd have been happy paying for Raven Shield with upgraded graphics, weapons and physics, but with the same core gameplay.
This seems to be a continuing trend in the gaming industry.
Heck, I still vividly remember my disappointment with the I'76 to I'82 transition.
While we're on the subject - what if there was a Raven-Shield-like game where one man in the squad was responsible for carrying "the bag". If you wanted to swap weapons or get more ammo (aside from what you were carrying), you'd have to go to the bag and get it.
Or perhaps the bag is just an item (albeit a large and cumbersome one), and anyone on the team can carry it and drop it, but while they're carrying it, they're slower, noisier, and can only use a sidearm. Imagine the tactics. (Ooh...covert bag stealage for crippling the opposing team...)