You don't
need to, but limping is certainly part of the optimal strategy. The ante, blinds, and lack of rake incentivize you to see a flop.
We have solved MTT charts with and without limps. Here's a comparison with and without limps 25bb deep:
As you get deeper, the SB starts limping more and raising less. You could even simplify this to a pure limp strategy if you wanted. Although you may have exploitative reasons to prefer raise/fold.
GTO Wizard