For us an entertainment system is not a must. We just buy the cheap dual DVD players on Black Friday and use that.
For me being a mom and transporting kids 90% of the time, the power slide doors and lift gate are my #1 must have feature. Especially if you have kids under the age of 3.
When we bought ours, we had a 2 year old, a 1 year old and were in the 2nd trimester with our third so we have felt that pain. We just didn't see the power doors as that important, and to date I've never heard my wife say "I wish we had that." And I agree you don't have to have the factory-integrated entertainment system, but you'll want something if you take long car trips.