Nah, the most important thing in chess isn't to capture more pieces than your opponent. The most important thing in chess is to kill the enemy king before your king is killed. That's why we love the Morphy-Allies Opera Box game so much-- Morphy sacked almost his entire army to win the game!
Accept or decline?
Both options are really great.
If you take that is good since hooray you get a pawn.
However the only way you can take is by decentralizing and moving the same piece twice.
I think the most important thing in chess is to capture more pieces than your opponent but that doesn't mean it is the only thing to think about.
In the opening for example the most important thing is to get your back row pieces into the game instead of remaining in the penalty box.