I think having the throttle at 0% by default is a bit more intuitive than the current, random 50%. I never saw a good reason for them to make that change, but when they did I assumed it was to shorten the amount of time you had to hold Shift to get to 100% (as the Z key hadn't been implemented yet). While I consider it to mostly be a general annoyance (though not as annoying as not having a navball in map view, or having crew assignment in the VAB rather than just before launch), I did have a few mishaps in 0.90 while playing around with RemoteTech and kOS. For fun, I wrote some kOS scripts to put a rocket into orbit, reenter and land, and a third to tie those together for a fully autonomous flight. At the end on my launch script, it sets the throttle to 0%, then unlocks the throttle so it is under user control again. Problem is, when the throttle is unlocked, it reverts back to the position it was in before the script was initialized. If I forgot to hit X before starting the script, the engine would start again, and rocket would spin out of control as I was out of range of any comms satellites. I think the throttle should default to 0% which an option to change it.