Because without a lawyer anyone would either get #1. no money or #2. a tiny nuisance settlement. Get represented by a personal injury lawyer who will fight to get you the maximum possible compensation.
Absolutely. You never want to try to deal with the insurance company yourself or you will get a tiny nuisance settlement at best. Find a lawyer with a low contingency fee, less than 30%, so you are left with the lion's share of the settlement, not the lawyer.