Well, while technically you're right about almost everything, I would like to give my answers as to why things were as they were. Also, this reply of yours perfectly illustrates just what seems to be wrong with rpgmaker in general.
1. My notion to show a worldmap instead of just a black screen or something was precisely to put the game into a larger context, showing the outside of the temple and where they may have come from. Though also the point of the opening text was to force the listener to listen to the music instead of skipping past it. But I will take this under advisement for the future.
2. Yeah, Popular Character Pack goes hard, but nobody's free to screenshot. :p
3. I hate plugins, all my homies hate plugins. But I concede I might have to concede on the matter, so, advisement etc.
4. Joel Steudler's music goes hard, too.
5. Yes, you're absolutely right about this, an embarassing oversight on my part.
6. That was by design. It's not a 'get treasure and level up' game, it's more like a ttrpg 'one shot' adventure where you don't even get to keep your stuff after. The whole point was the adventure in itself. Now, in a more involved game, there will be ways of advancement, but that was not the point of this one, which would not even have the capability of being 'involved' unless I made some dungeon randomizer thing.
7. That was more of a concession for the game jam, than anything. Though it does stand to reason that they would have brought stuff with them when sent out to do it.
8. This is inaccurate, in at least one respect. For the Fall boss, I actually designed it to be strong to melee but weak to magic, as well as specifically setting it to be weaker to fire magic. So, that was her time to shine there. Winter and Balance had the issue though of me setting them to reflect magic.
9. Honestly I didn't even think about his 'ultimate attack,' I just set everyone to level 20 as a matter of course for this one shot gamejam game. But I will describe what I intended: The Balance was meant to have a little bit of every boss's power, so regeneration AND magic reflecting. Also made him a little more evasive. However, on the whole, I know that my balancing would be hit or miss, and thus I basically agree that it needs serious improvement.
10. Yeah I guess that was lazy of me.
Also, here's a couple errors you forgot:
1. I used sample maps. My own fault for waiting until literally the last day to throw something together.
2. You could also argue that zero direction about what exactly to do was a fault as well.
EDIT: forgot the thing about the top battler...well, I have reasons for preferring it in most cases, but I'll take that under advisement as well.