I’ve deposited some CRV to my MetaMask.
Now I want to send them:
It says I need some ETH to pay the fees.
Okay. I am fine swapping some CRV to ETH to pay the fees to send CRV:
But it looks like in order to swap that I still need some ETH in the first place! 
It that by design? Are my CRV now locked in MetaMask unless I deposit/buy some ETH?
You need the native coin of the network you have those tokens on to pay for gas fees to transfer them out.
Understandable.
What’s not understandable though, is why the user is forced to suffer? Why not to design it such that part of the ETH to be gained from swapping is used to pay the gas?
In the various available EVM-compatible networks, gas fees are currently paid in network-native tokens: for example, ETH is required for any transaction on Ether; BNB is required to use BSC; POL (formerly known as MATIC) is required to use Polygon
As far as I know some smart contract wallets currently support other limited tokens as gas fees.
Right, so this is a feature request basically. When swapping to ETH with no ETH to pay the gas, lend part of the would-be gained ETH to pay for it (and deduct the loan amount once swapping is complete)
I actually found MetaMask searching for an open-source non-custodial wallet for CRV. I neither had nor cared of ETH. If I knew that MetaMask only allowed operating (swapping/sending) CRV provided that I also had some ETH, I would perhaps skip MetaMask.
This would be the case for all wallets, not just MetaMask. Requiring ETH for gas fees is because of the Ethereum blockchain, see here on our Knowledge Base for more info:
