second, When you are a company as large as AB/Inbev you MUST cut costs in order to increase profits. and you MUST increase profits (note to less careful readers, I'm talking about INCREASEING profits not simply MAKING profits) There are two ways to cut costs, cut labor costs or cut materials costs. given that Budweiser has dropped from ~17 IBU in the 1970's to ~6 today you can see where they chose to cut costs.
This is true if you can no longer expand your market share but these acquisitions are about expanding market share. They don't need to cut costs on a wildly profitable business. At some point in the future, if craft beer fades into obscurity, perhaps these acquired craft brands become diluted. I agree with the line of thinking that ABI's ultimate goal is to retake control of tap handles and shelf space by creating a single package of macro plus craft that can be sold to distributors and retailers and squeeze out the competition with the illusion of diversity.
I generally disagree that ABI cuts their product to save cash. They go to great lengths to brew beer in a non-cost effective manner, such as mashing for four hours and using beechwood to clear the beer when they could just as easily centrifuge or filter in less time. The reduction in IBUs was not done with cost in mind but with consumer preference. As Americans consumed more sugar from the 1940s forward the preference for sweeter beverages went with it and AB products followed suit.
I can't begrudge the business owners who decide to sell. It's nice to think about the philosophical stance of protecting the craft but by the time you're at the top of a brewery the size of Goose Island or Breckenridge your job has no connection to a craft. You're just managing a business. You aren't brewing. You aren't designing new recipes. The bigger the company gets the more removed from the production you get. It's far easier to take a profit on something that feels like any other management job and get your uninvolved equity holders a payout and go do something else.