I dont understand the whole controversy. Most people aren't even aware that the kegs cost the breweries more than $30. If the breweries were concerned about having the kegs returned instead of losing the $30, i would think they would make you sign something that states you're 'renting' the keg, or just make the deposit $100. Let's be honest, if you have a draft beer set-up and you wont miss $30 being tied up, is $100 really going to make/break your month? Sure it sucks, but you know you'll get it back...
My favorite local microbrewery charges a $100 deposit, and it has never detered me from getting a keg of their beer, but it does assure them that they're gonna get it back!
I've had an empty Miller keg in my garage for about 8 months just because i haven't gotten around to returning it... no real incentive...
As far as I'm concerned, when you pay for the beer, the keg becomes yours... The brewery might pay more than $30 for them, but by only charging a $30 deposit, and making no effort to recover them (or even inform buyers that it's the 'ethical' thing to do), they're essentially valuing the kegs at $30...
They're big companies with a lot of people who get paid big bucks to figure these things out... if they're ok with letting someone keep a keg for $30, so am I.