Agreed - I appreciate the sheer variance in comment quality and the threads are easy to consume. To take something like /ck/ (cooking), you have a mix of some generally good advice, along with a fair amount of madness and absurdity. The mix works for me. I am glad they split off the "work-safe" boards to 4channel.
I agree that it probably has had little effect on the site overall, and huge quotation marks as you say. I am assuming they did it for more flexibility with advertisers or something.
For me it is more psychological--there is a fair amount of decent content there, but being one click away from /b/ and /pol/ can be a detriment if I want to share a link or show something to my girlfriend. "Here's a bread recipe that sounds tasty or some /diy/ project--but don't use your work computer and you might want to fire up VPN."