I think deferring is vastly underrated. Not only does it help with finaid (as you get older, HLS looks at a smaller percentage of your parent's income when determining aid), but it might be your last chance to do something really crazy. I.e., unless you want to do international law or human rights, there's no good justification for going to Thailand for a year during or after law school. However, do it beforehand and no one will bat an eye. HLS opens up some doors, but those student loans sure do close others.
I don't know if "vastly underrated" is the right phrase, since fully 76% of HLS's class last year was not K-JD. Pretty solid majority.
I think taking time off can be, in some instances, overrated. I was pushed by several acquaintances to take a year off after undergrad, despite the fact that my biggest interest is to practice law. In my case, the main consequence of taking a year off would be putting off the repayment of that student debt by another year. That's unattractive, since I'd like to get out from under the student debt shadow as early in life as possible.
All in all, if you have a specific interest or opportunity that makes you consider deferring, definitely do it! But don't do it just because others are doing it.