I only use it when speed is important, so I guess it's mainly for that. Only ETH that I hold anyway, the exchange fees of like 0.25% or so are usually higher than the network fees.
Issue is, its only going to get more expensive as prices rise... BTC is certainly not a transactional currency in its current form.
RE: PSA - Kraken Exchange is Raising Withdrawal Fees, Dynamic Fees Coming Soon - UPDATED SCROLL TO BOTTOM