It doesn't work exactly like the prequels, that's my whole point. It works exactly like the one with a winning recipe, which is C&C1, but with an extra faction, better controls and better graphics. Unlike Generals it didn't take only a single day to get through either, which is a plus.
Of course you need new elements, WC3 definetly had new stuff compared to WC2, but that means you spice up the recipe, not change it. There's a difference between making a clone and making a proper sequel - a clone would be identical, a sequel would have more of the same, but with sugar on top.
Remember, we're talking about sequels here, not completely new games. I'm all in for trying out new stuff, but in the middle of a game series is just not the right place for it. When you create a successful franchise, the fans want a certain something, and that's what you provide them. When you make a new series, such as Gothic back in the days, you need something that will make your particular game stand out, such as features the world has never seen before.
There's a difference between starting a new series, and continuing on an old one. In my opinion, developers should stick to the winning recipe which the series was based on when making sequels, but try something completely new when making new games. Clones are the result of something copying someone elses' game/series, a solid sequel is the result of a developer that manages to keep enough elements from the previous titles, but spice it up a bit.
What do people that cry for SC2 to be different than SC1 really want? New factions? New setting? There's only so many things you can do to alter the ways of a strategy game, and I honestly don't think the fans would be happy if Starcraft 2 suddenly came with different factions or a new setting. In fact, the original has reached such status by now you'd probably get a worldwide rebellion against Blizzard if they replaced one or more of the factions in Starcraft.
