While your basic points are not wrong you're extrapolating farther than these ideas are actually going. The destination is set the path is not. Many paths lead to the same end and the event is no more trashed because someone did something differently than the Ball was ruined because how players responded more or less made the plot irrelevant. The idea is give people something to do and a reason to be in game not to try and explore every single what-if in one event. To be fair, the larger the event the less likely you are to even have a wildly out there solution since most people will go with what the group decides even if a wild one occurs to them.
However there are even problems with assuming that an RP always has to be fully open ended and that you always have to take on the grand sum total of all possibility even when you try to plan even the slightest RP action. It makes it feel too burdensome to try to run events since you have to try to account for everything. Too much is expected for anyone that even attempts an event. It's why it's so burdensome even for you to run events. You make it so that it requires more of you than it needs to and it burns you out if you don't have enough return. You take on way more effort than you will get back. If nothing else, balance the equation.

Effort put in = RP return you can realistically expect for your investment.
You'd see more events overall if running events wasn't made like carrying Atlas' load. Not to mention, you'd see more variety because people wouldn't stick by the "safe" ideas and do mostly the same events over and over. People are scared of getting chewed out for a "failure" when a learning curve, or even an outright fail is not the end of the world. Even if the idea of predetermined ends gets your goat, it's an easier model for an event. If all else fails let people get some practice in and then maybe you'll have more people to work with who will go on to do the more complex open ended events. As it stands, people will never get experience in running events because the idea of even attempting one will be too scary or they will get shouted down if they don't do an event exactly like the ones preceding theirs.
Also, as I said earlier, flexibility... If you need to adjust an idea to change an outcome to work logically then do so. What's the point of being on hand for your own event if you aren't going to keep it going? Sometimes someone has to stop playing for a sec and actually manage the event. But I noticed something over the last few years Rig... We talk a lot about having options and players coming up with event breaking ideas and you know what the reality has been? It almost never happens... Most players stand around either wondering what to do or will pick the most obvious answer even if it is an open event and there are 50 million possibilities. Regardless of why it happens, it typically does. Larger scale events don't run like an RP with 4 to 10 people. It's why people who run complex RPs often complain that they don't get explored fully. How often can you remember a "baddie" character being met with "kill it" and "kill it faster" which bypasses the story? So rather than make a Sherlock case out of it, these ideas are straight forward. There is an overarching resolution but some wiggle room in how you get there.
But, if you have no use for the alternate paths to the same end then fine. If knowing the end result is too much strain for you to RP under then fine. Do like I had to do with dark events and events that could easily get hijacked into those themes, avoid. Not everyone can adapt to every kind of event. Or, if you prefer, modify the idea to better suit your tastes.
Some people like to follow the cruise director around and others like to wander away to explore on their own.
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Exactly. As I've said, it's a matter of taste.

If it were inconceivable we wouldn't have these conversation periodically as the idea would never occur to anyone to do differently.