So, I’d just like to say as a Blender and UE4 user I do not feel in any way entitled to support for Blender by Epic Games, and that I am immensely grateful to Epic Games for their $10,000 donation to the Blender Foundation to assist in the FBX pipeline from Blender to UE4. I even had the honour of meeting a number of the Epic Games staff in September 2014 in London at EGX, just after that donation was made and expressing my gratitude to them personally.
Any ways I think that Epic Games does value Blender as a 3D content creation tool for Unreal Engine, hence why they made that donation in the first place. And of course Blender is a valuable tool in content creation for games, that much is clear. I am currently developing a game with UE4 and all my content for the game is made with Blender 3D and I have next to no problems with the current FBX export from Blender to UE4. Which is thanks to the advancements in the FBX exporter / importer made by the Blender Foundation after the donation from Epic Games.
That being said, I feel for Bastien Montague and his problems trying to stay up to date with FBX in Blender. And I can understand his frustration with anything made by Autodesk! 
But maybe this debate has got a bit out of proportion. At present the Blender -> UE4 pipeline works just fine. It could be improved, yes, but it works fine. And while I sympathise with Bastien’s woes, I think it is really essential for Blender that the Blender Foundation continues to support whatever Import / Export Pipeline is best for Unreal Engine. And I hope that will always be the case.
If significant changes or updates to the FBX SDK are made in the future, and those updates need to be integrated into Blender, perhaps it would be appropriate for Epic Games to make another donation to the Blender Foundation to support that? Perhaps that would make Bastien a bit happier to continue supporting FBX or whatever file format works best for Unreal Engine. 