Same reasons you use an L2 on Bitcoin. You would use L2s on Monero for instant and much cheaper payments. Offchain txs can also be better for privacy especially when combined with an encrypted base layer.

There doesn't have to be exchange risk with Monero either. There are several atomic swaps out there between BTC and XMR like UnstoppableSwap, BasicSwapDEX, and soon Serai if that is what you meant. You can have wallets that do the exact same thing in the background. Cake and Stack already do this.

Ok sure, but you're only getting around force closes this way by taking on intermediaries like LSPs meaning you're asking permission to transact and introducing privacy implications.