Focusing on the cost side of software development is not very convincing for managers who need to make purchasing decisions. I believe most software is a high-margin product because manufacturing costs are close to zero. Even a relatively high difference in cost is not as much as a small difference in value. The one cost-side metric that has a big effect on value is time-to-market.

What could be more convincing is the effect on product value that build times could have, and they certainly could (and I, for one, believe that they do, especially if they can be made to be less than 15 seconds or so). For example, it's certainly conceivable that very short build times make it easier to write more tests, which could result in more correct software with better features and/or a shorter time-to-market.

Some products targeted at developers also make the mistake of focusing their marketing message on the cost, perhaps because that's the part of the business that developers personally feel, but it's not the message that would convince their employers.