I think mostly everyone uses it because its the most used wallet on ETH. My friends are also using it because you can easily manage it and you have a lot of coins there.
MEW can not be easily hacked because it is good secured.
Indeed, Myetherwallet is actually more secure because it is decentralized and source code is transparent and available to the public. The most interesting about this wallet is the security and the only thing you do is to protect your digital wallet and private key otherwise myetherwallet has no liability.