They're managing the daily deluge of DDoS attacks and you're paying for less than 0.0001% of that because a million other customers are sharing the burden.
Sure, your website never went down, but now you have an infrastructure bill you'll have do do another round of funding just to pay off.
In terms of application-specific attacks, we have used proxies in AWS to mitigate attacks against our colocated servers from time to time. AWS handles some of the volume and some of the types of attack traffic, and we scale and cache to handle others. This was much cheaper and easier than some of the Prolexic type solutions.
Agree that they aren't doing anything specific on a host or customer basis, but just inherent in protecting all of their customers, some of the specific problems also go away.
At only 7200€/month for a 100Gbps line, the network won’t be an issue in case of a DDoS for you anymore.
DDoS’es over 100Gbps will be irrelevant anyway for you, because at that point your ISP will already getting issues.