we are saying the same thing.
legacy does not have any EAC requirements, so you can launch it from either the .exe or steam.
experimental requires launching through steam because that's how EAC is launched; without EAC experimental will boot you every time because it requires EAC to be running to allow you to join a server.
but i agree, the issue is not being able to launch through steam. have you done the basics, like restart steam, restart the computer, wipe the cache, check rusts file integrity etc etc?
*edit*
probably worth posting your specs too, just in case.
I assure you it has nothing to do with my specs, but alright.
And yes, I have done all the basics, numerous amounts of times.
Operating System: Windows 7 65-bit
Processor: Intel Core i7-4470k CPU @ 3.50 GHz(8 CPUs), 3.5 GHz
Memory: 10192 MB RAM
GFX: NVIDIA Geforce GTX 770
( Sorry if it's missing some things, I've never posted specs before. )