Why won't Starcraft II live up to the best RTS of the past decade? Because the best RTS of the last decade was Total Annihilation.
I'm not sure I agree with you on that point - I own TA, and my friends and I played it, well, sparingly. TA was fun for a short while, and it was a good game, but I would hardly claim it's the best game of the decade.
Frankly, the second best RTS (or at least the most original and innovative) of the last 10 years was Supreme Commander.
Once again, I don't agree with this. Perhaps to you they are the best two games of the past decade +1, but I would like to see some evidence.
The best games are games that innovate, but still manage to provide a solid gaming experience. I agree with the poster who stated that innovation doesn't count for much if the game isn't fun. Games with little 'new' features can still be fun if they are polished and play well. However, they can get a little dull after some time.
Really, new features in games make them fresh and exciting, and are absolutely neccessary to keep a genre alive. However, developers must find the fine balance between innovation and good gameplay. A game may be totally original, but if it's completely foreign, people usually won't enjoy it. Then again, if a game uses the same old conventions, but pulls them off seamlessly, then it usually will have some longevity because it will be fun. Unfortunately, then it seems to come down to which developer has the most funds to make it look better and can take time to 'polish' it. I played Starcraft for years with my friends, and we also played a bit of Warcraft 2 and 3. I enjoyed all these games, but Warcraft became a little tiring after a while.
The problem was that when playing against my friends, I could effectively use similar strategies over and over again to win. I was the fastest with a mouse, and knew the shortcuts better than everyone else. Therefore, I always won. Now, I realize that Warcraft has far more depth than this, and that playing online would present other new ways of playing, but the pattern would be the same. You learn a few more strategies, then you execute them. If you can micromanage better, you usually win. Besides, the real 'magic' of a game came out when my friends and I would get together and play. The internet always felt like an advanced AI player to me, and winning usually gave me very little satisfaction. I know that isn't true for everyone though.
As great as Sins is, it doesn't do anything terribly new, but the way it presents it's features is innovative. I would like to see a little more depth, and more methods to win other than total conquest, but as a whole, Sins is greater than the sum of its parts. Sins provides solid gameplay, while presenting RTS conventions in a new manner. Also, the focus has been shifted from micromanagement to macromanagment for the most part, and this is refreshing for those who don't click as fast as others. I can't wait for the expansion, as I hope to see greater depth in Sins, and that Ironclad continues to innovate in its developments.