What more can I say!? I´m really disapointed and let me say I not alone even if "MANY" users have asked here for that option.
Yes, you are basically alone, but we had countless request to always get at least a straight pusback, so we added it. We'll see what we can do with this additional request.
See my point of view. For me it is a very easy thing to add a pushback to parking positions where it is missing (ADE e.g.) But right now I see no way to delete it from GSX ...
One last question. Is there a possibility to switch back to the older version?
No, there isn't, and it would be very wrong doing that just for "the atmosphere", because you'll lose a lot of other improvements that would "kill atmosphere" much worse than the odd pushback in the FEW places where pushback should be really disabled. 90% of the times, a "None" pushback was the result of developer oversight.
And in any case, the older version had the opposite problem: once you set a parking to "None", there wasn't a way to get a pushback there, unless you reset it with the editor. Which means, with the older version, you couldn't simulate a situation were pushback is NORMALLY allowed, but for some reason you don't need it for that flight, unless you left the parking always enabled, and enter in the GSX scenery editor to set it to "None" for THAT session. And THIS "kill atmosphere" MUCH WORSE than having to start pushback and then cancel it, because it required exiting from the flight for a moment.
So no, the old version wouldn't solve anything and, as I've said in my previous message, we should probably add a NEW separate option that wasn't there before, to explicitly disable the pushback so, if that option is selected and the preference is "None", you'll get the straight pushback, but if that option is enabled, the pushback will not even be an option.