Why use 1-way state pegs instead of atomic swaps or 2-way asset pegs?
Simply put, Cross-chain bridges are a better solution than Atomic Swaps. Atomic Swaps involve a complex process of signing cryptographic keys between two parties that require interactivity. You also need a counter-party on all trades. Cross-chain bridges, coupled with continuous liquidity pools means you don't need a counter-party, and swaps can happen in less than a second.