From which perspective do you want an answer? A user of Microsoft products, a developer at Microsoft, a shareholder of Microsoft, or an executive of Microsoft?
As a user, of course I want Microsoft to invest more in speeding up their products. I also want them to be easier to use, and have all the features that I want, and cost less, and release more frequently.
As an engineer, yes, I do want them to invest more in speeding up products. Performance tuning is fun, it's an extra skill that can go on my resume, and it helps me take pride in my work.
As a shareholder, hell no are you going to indulge those prima donna engineers and their perfectionist tendencies. I invested in this company to get a return on my investment, and that means more revenue. It's clear that shaving CPU cycles isn't going to get more customers; Windows has been dog-slow compared to competitors ever since the Amiga came out, and it hasn't hurt us so far. That effort would be better invested in getting into new lines of business and building more solutions to capture the enterprise market.
As an executive - it's a complicated question. I want our products to be faster, but it's also clear that our customers want them to be easier to use, and have a lot more features, and cost less, and release more frequently. All of those are in conflict with writing performant code with a fixed number of highly-trained engineers. And if I hire more engineers, the code often gets slower, as global optimization opportunities get lost in the communication gaps between workers. OTOH, performance often has intangible benefits in brand loyalty, in increased usage, in word-of-mouth, and in PR. I'd love to be able to quantify these benefits and trade them off against each other, but the point of intangibles is that they are intangible. I'm responsible to shareholders, however, and my gut feeling is that increased performance will not be the deciding factor for most customers.
(As just plain old me, the question is completely academic: I am neither a user, employee, executive, or shareholder of Microsoft, so I don't really care what they do.)