With the advent of DACs and decentralization through parallel and independent chains proof-of-work does not scale as there are too many potential chains. The CPU power created to mine one strong chain can kill a baby chain. The result is merged mining, but this only works for compatible mining algorithms and has other overhead.
1) Eliminate the need for Merged Mining to Scale in Parallel
2) Eliminate the need for Centralized Mining Pools
3) Eliminate inflation in coins... from the perspective of a DAC this means decreased costs and increased profits. End result: increased share-holder value.
4) Eliminate 51% attack and Selfish Mining Attack
Benefits of Mining:
1) Socially beneficial proof of work (Primecoin?).... there could still be a DAC for this and there is no need for this to be part of every coin.
2) Viral Marketing and Initial Distribution of Coins .... useful early on, there are many ways to achieve this without depending on it long-term.
3) Advancing Technology? Perhaps, but I contend that we are a long way from being a driving factor in general purpose advancements. The profits available are already sufficient to motivate the best talent to improve general purpose computing (CPU/GPU/RAM).
The Cons of Mining:
1) Leads to centralization due to economies of scale.
2) Distribution method causes Amazon and DO to profit from the issuance rather than the developers.
3) Favors Botnets and encourages this kind of crime.
4) Can be a easy point of control for governments.
The Cons of Proof-of-Stake?
1) How to distribute coins? Many options here.
2) Variable transaction volumes make confirmation time unpredictable?
3) Difficult to pre-verify chain by block-headers alone.