[contingencies]

Setting aside the cultural baggage of its authorship and nomenclature, from a purely objective standpoint I could not pass Introduction / Motivation without attempting to elucidate the objections I felt to its generalizations.

The most frequently cited architectural flaw is the lack of a coherent security design: The success of IP is simplicity/general utility - the ability of the system to support different use cases as a packet-switched alternative to previously dominant circuit-switched telephony systems. This is precisely the capacity of the system to vary service types and levels based upon application requirements. Viewed in this lens, not having a 'coherent security design' is the core feature, not a bug.

many question whether the basic service model of the Internet (point-to-point packet delivery) is appropriate now that the current usage model is so heavily dominated by content-oriented activities: CDNs, content-addressable P2P networks (torrents), and multi-mirror package management databases are all excellent, broadly deployed counter-examples. The fact is, by normalizing packet-switching, IP has made bandwidth so cheap that inefficient distribution becomes a trivialized cost. Again, this is a core feature.

[oscillatingfans]

A system cannot switch the service type to "prevent DDoS from spoofed IP packets" though.

The authors are not arguing against packet switching; they're questioning whether point-to-point still applies when a majority of the Internet is used for accessing content. CDNs aren't cheap, a content-centric network (e.g., https://en.wikipedia.org/wiki/Named_data_networking) could substantially increase efficiency.

[contingencies]

There are many effective DDoS resistance strategies. However, if you had to build those costs in to the core of the internet, then there is a fair argument that it may never have taken off as overheads would have been too high.

For the NDN concept, again the whole point of IP is that you can implement it on the same base: Upgrade cost of network complexity: The Internet has smart edges ... and a simple core. Adding an new Internet service is just a matter of distributing an application ... Compare this to voice, where one has to upgrade the entire core. - RFC3439 (2002)