It's best not to think of fees in USD terms, since fees are tied to the protocol. When the price of BTC increases, so does the USD cost of fees. It's also true that fees have risen in BTC terms, but just pointing this out because it tends to exaggerate things.
From what I've been reading, Coinbase has big problems with their UTXO set. It's massively fragmented. I'm guessing that if they optimized their wallet protocols and transitioned to Segwit when fees were very low a couple months ago, things wouldn't look so bad. As it is, the combination of network congestion and their UTXO set is not only driving your fees higher, but it's probably making it impossible for them to implement Segwit, which could drop fees in half.
We've seen similar spikes in the past and they always die down, though this is by far the worst. In theory, the high fees should quell demand (or start to bleed a spam attacker's wallet), which will eventually calm things down.