Agree with only do it if it is likely to be enjoyed for what it offers. I don't think anything should be done for the sole reason of adding to uni applications. I do know plenty of parents who encourage their children to do things because 'it will look good on their uni application form'.
My own D of E experience:
DD, heading off on French exchange, "Mum will you complete and hand in my D of E form?"
I dutifully did.
DD after first D of E meeting, "Mum you never told me I had to hike and camp
Well duh, everyone knows that about D of E
She had clearly done a lot of research before signing up
Needless to say she didn't continue with silver or gold, but she did take something from the experience and has continued volunteering with RDA, 4 full years so far and organised a further French exchange independently.