Thanks Bob,
what do you mean for deposit address?
my personal bitfinex deposit address works quite diffently...
this one doesn't look like a "normal customer" deposit address
It's probably just an internal address... It's normal for exchanges to move funds around between wallets, create change addresses, combine many unspent outputs into one to minimise fees, store BTC in a cold wallet, retrieve BTC from cold wallets,... It's probably not a customer's deposit address since it received ~1400 BTC in ~1600 tx's.
In reality, it doesn't matter why bitfinex chose to use this address, they'll probably have their reason (technical, emotional, practical, security, minimising fees,...), however i doubt you'll ever know the exact purpose of this address without asking bitfinex directly.