I'm gonna make this argument real easy for Nexon to understand.
1. "The reason we switched our service to UTC was to standardize the time zones between our European and North American servers..."
While showing consideration towards our European counterparts is a very good thing to do, there's nothing you can do about them being an entire ocean away and thus operating on different times, which means that no matter what time you pick, you'll never be able to sync our time zones for optimal play for everybody. No matter what time zone you pick, there'll always be some inconvenience. So if there's going to be inconvenience anyway, why not pick a time zone that would give consideration to the greatest amount of people rather than their geographical location.
2. "...and make it easier for us to plan out event times and such."
You did not make things easier on yourselves because you never got rid of your PST mindset so now, you're operating on two different time zones rather than one. Server resets are UTC and whatever the hell else is PST. As the New Year's Shop fiasco has demonstrated and the fact that this Valentine's event didn't even start at UTC midnight or PST midnight for some inexplicable reason, it's clear that even you can't keep track of your time. And if you can't do it, what makes you think your players will? It's like planning half your life in one time zone and half your life in another. Operating two different time zones is complicated and unnecessary.
3. "Now, we do realize it did cause previous events, previous reset times, to be a little bit inconvenient, so we are looking into that."
Things are still inconvenient three months later. This whole thread is about how inconvenient it is for everyone. With this new setup, you've effectively wrecked many people's ability to participate in events or finish whatever they need to finish before the reset. Even your workaround regarding the 2x and Spell Trace by dividing it up into three parts is unnecessary if you just made the event last a whole day (but don't do that before you fix this horrid, horrid The Lag).
4. "But we do want to make it convenient for, not just people in North America, or Europe, specifically, but all of our players all around the world."
You cannot please everyone so stop trying. By trying to cater to absolutely everyone by finding middle ground, you make things equally unsatisfactory for everyone instead. As previously stated, show consideration to the greatest number of people rather than their geographical locations.