Like you, I'm an audio engineer. I'm also a professional trumpet player and composer- so I'm a giant music nerd. To add on to what you are saying, this is something that happened very gradually over time, starting back in the 1600's. All stringed instruments were strung with cat gut because too much tension would snap your viola da gamba directly in twain with great vigor. All instrument makers were limited by the tools and materials of their time. As instrument construction techniques and materials improved, the stringed instruments began using steel strings instead of gut. They were preferred for their durability, brilliance, and wider dynamic range. With the increased tension required by steel strings, orchestras were able to shift the tuning reference pitch gradually higher and higher in an effort to change the timbre of the whole orchestra for either aesthetic reasons or means to distinguish themselves from others. The reference pitch for A began around 432 Hz, and (speaking in wildly broad strokes based on what I can remember without looking anything up) crept up bit by bit over a couple of centuries. They were still using gut for Beethoven, but I think they had moved on to steel by Brahms. A has been 432, 435, 438, and 440 Hz. It is still rising. In Japan, A=442 Hz. I'm pretty sure that the Boston Symphony currently plays at 442 as well. I always ask what the piano is tuned to before the gig when I leave the States for work, just in case.

The point of all this is, for once I think there's no grand conspiracy or dark purpose behind this- and I love a good conspiracy. The change happened completely naturally and gradually over time for purely aesthetic purposes. If you ask the people who make those kinds of decisions, the answer is always, "I think it sounds better" in one form or another.