You do have to consider that this is an 8 core, and more and more applications are being developed with this in mind. Whoever still thinks that Single threaded performance is the most important, lives in the past.
That's not true. 2 weak horses != 1 strong horse. 1 strong horse can do the work of 2 weak horses, but not the other way around. A single core can run multiple threads, but multiple cores can't work together on a single-thread task.
Sure, but Excel is presumably one of the most optimized (in terms of the amount of money and brainpower devoted to optimizing it) applications in existence.
That's the price of backward compatibility. But I think it's a bit of a "Seinfeld is unfunny"[1] situation; if Microsoft decided to save on the nine-figure budget and outsource Excel development to, say, your favorite purveyor of antivirus software, you'd notice real fast.