I was a Hulu subscriber long before D+ came along and signed up there for the whole Hulu/D+/ESPN+ bundle when they added it. The bundle is managed and billed under Hulu but D+ is billed separately and somehow credited back off the bundle price in Hulu.
To get things under D+ now I'd have to wipe my account and do it from within D+ again, losing all my data from Hulu in the process.
The only good thing about them consolidating might be simplifying all that.