till today, i am still using coinbase.. have more than 2years.
I use more wallet, coinbase, blockctrail, block.io, blockchain, mycellium, also xapo
but my main address at blockchain and mycellium
Having multiple BTC address's a decent defense to make sure not all you BTC disappears if hacked. This way you only loose one wallet which is good.
If you have all your eggs in one basket. It's kinda a single point of failure and you are done.
I`m not sure if it defends you against a hack. If you hold on a cold storage, and somehow you get hacked (by guessing the priv key from the signing variable being compromized), then you might be more cautioous if you hold it on another variable.
But other than that, if you have it all online then its no use. If a hacker gets into your PC, he will most likely steal all your bitcoins.