This has been hashed, rehashed & re-rehashed. It's a business decision & it's odd that that is perceived as "giving the full finger". It's not b/c EN hates linux and/or linux users. Anyone who dislikes the existing options (IE web client, Nixnote) can use the EN API to build their own linux client, if they'd like.
Sure, its a business decision, and sure they can do whatever they want. But with enough squeky wheels they may find 1.) there is a big enough market out there and/or 2.) they are alienating a group of people and getting a bad corporate rep.