Regarding the 'game balance' issues with having a monster spawn slider (or multiple sliders if you also want to control how quickly the tougher late game monsters make appearances).
Yes, the 'default' position of the slider should be where the game is balanced. Those of us that choose to deviate from the 'game norm' understand that we do so at our own risk. Some of us like that extra risk and living on the edge!
And the slider 'default' can be linked to game difficulty (so normal difficulty has 'normal' monster spawning, while difficult level has 'difficult' monster spawning.
Some players genuinely hate monster hunting and there is an option in the game to remove them during setup. Other players don't mind occasional monsters, so they should have that option, if they so choose.
Some of us like eeking out our existence in a dangerous world where the monsters are as much or more of a threat than the the other kingdoms/empires. Let us live the dream/nightmare!
Now, in an online game, at that point ALL players have to live with whatever difficulty is chosen. But what goes on in solo games really should to a degree be left up to the buyer of the game. If Stardock can tailor the Elemental experience even further for varying tastes, so much the better.
If we were bragging about our high scores, and these were 'tracked' by Stardock, that'd be another matter. But since each Elemental game is unique, and since we aren't posting our high scores, our individual game settings are really only relevant to ourselves.
There is an older game (the Warlords I, II, and III series) where, on custom maps, you get to choose how many cities, bonus sites and ruins appear ingame, how many landmasses the game has, as well has how many 'dice' are rolled in combat (to reflect whether you think quality or quantity should be the bigger factor in combat). There is no reason Elemental shouldn't have some or all these options eventually, in my book.