Was Expanse war on Ethereum with their fork? I can understand the concern but declaring war seems a little dramatic.
First of all, I am of the opinion Expanse is a pump and dump. Look at the lead developer's track record of failed cryptocurrencies with "gimmicky" innovation, dwindling market capitalizations, and over-promising yet under-delivering. First Franko, then Aiden, now Expanse.
Explain how Expanse was/is a positive occurrence for Ethereum?
Yet, you are comparing Apples and Oranges....
The guys behind Expanse are not (and never were) involved in the Ethereum community. See their Ethereum forum profiles and Githubs:
defaced:
https://forum.ethereum.org/profile/defacedhttps://github.com/franko-orgCryptoCc:
https://forum.ethereum.org/profile/CryptoCccan't find anything easily on their 3rd "founder"
My point with showing that information is that the Expanse fork is not a hostile takeover (a la Tonyk's fork) within the Ethereum community. If Expanse formed out of a disagreement within the Ethereum community, and a small but substantial amount of developers/community left expanse to work on the new fork, then yes it would certainly be a bad thing for Ethereum. The public perception alone that the community is splitting into two competing cryptocurrencies is a huge negative force on the market.
Further, you could still argue that since they are "working" on Expanse, that takes away possible developers (and therefore value) from Ethereum in the form of possible smart contracts that never materialize. Furthermore, Expanse community/volume/marketing certainly takes away from the Ethereum community/volume/market cap. Without its existence, these people likely would have participated/invested/traded/developed in Ethereum instead... they did choose an Ethereum fork after all.
All cryptocurrency forks are less successful than their counterparts. I can only name one anomaly (Bytecoin-> Monero), and I think that was an extreme case of an unfairly launched Cryptocurrency . Ripple dominating Stellar. Bitcoin dominating all alt coins. Litecoin dominating all of its forks. Ethereum dominating all of its forks. Nxt dominating all of its forks. Peercoin dominating all of its forks. Bitshares dominating Muse. Yet, Tonyk's fork is going to be a great success, provide a liquid smartcoin exchange, and all of us are going to switch over to it.
Expanse did not sharedrop Ethereum so perhaps it was even worse than this scenario. Then again maybe not, it is hard to compare apples and oranges.
In summary, since it is unlikely the fork will be successful, and it also takes away developers/resources/community/volume/cohesiveness/market confidence/perception of success/etc., a cryptocurrency fork is like declaring war on the cryptocurrency it forked from. It has little chance of success, and is certain to cause negatives that would likely not otherwise occur if the chain wasn't forked.