I understand what you are saying, but that's pretty much what happens on every RPG, if you find my game annoying for doing this, you must hate every type of RPG.
But I agree on some parts, so what I will probably do is add a hint to what level should be good enough for this event and the next one, hopefully it will help some players in the future.
While I do try to take into account the people that like to rush (that's precisely why I will not let people save on this event, to avoid them bricking their save and complaining about it later), it's not my fault if they are ignoring all the warnings and end up getting their ass beat by some enemy.
Everything comes back to interpretation, if the player assumes that a "tough fight" can be won by killing a couple slimes and buying 2 heal items, failing it is entirely on them.