I'll echo Fenes comments from above. The reason for including the Blue Slime is not to be a challenge. It stopped being a challenge a while back and turned into scenery. It brings the world to life and gives it internal consistancy.
I realize that those are not priorities for all gamers but they happen to be for me (and many others). So that is the point of including them.
True. You can certainly do this and there is nothing wrong with it. I will often skip through the details of such things because my players get bored pretty quickly unless interesting stuff is happening all the time. They want things that are a challenge to defeat to fight. They want the things that happen in the adventure to be important to an interesting story.
We've tried a sandbox like game before and our DM had a lot of fun describing what happened....for the first 3 or 4 hours. Until she realized that she was going to be describing, in detail, our one night at the inn for multiple sessions straight unless she took some control of the game. It was around the same time in the game that half the table was beginning to get bored of sandboxing it as well. I was looking at the clock and thinking "We've been talking to people in a bar, picking up women, drinking, playing darts with locals, role playing our characters now for..how many hours? Wow. I mean, it was fun for a while, but I'm a fighter and I'd like to use my sword at some point."
Then the DM had someone come up to us and recruit us to go into a dungeon and we were all happy for the change in pace, and we proceeded with the dungeon crawl. All the monsters in the dungeon were level appropriate and there was a big puzzle to be solved to get to the end.
The point is that you can use "color" monsters as long as they don't spend much time on screen and don't occupy much time. It's fair enough to say "You are so powerful, the guards don't even stand a chance, you kill them all and take all the treasure out of the vault, you have have 300,000,000 gp, what are you going to do now?" It's another to have an entire campaign where you don't make attack rolls because it is all roleplaying or fighting enemies too weak for you.
But for me, it makes a much more exciting story(which is what I'm trying to tell by playing the game) if the PCs go through trials that challenge them. Much in the same way you rarely see great heroes fighting things that are no problem at all for them in movies. But I am aware that this concept is pretty much the exact opposite of sandbox play(which is generally pretty simulationist). The idea of simulationism and sandbox play is that "things are there because they are there...I'm not about to skip description of them simply because the PCs are too high level to care about them." But, I agree with other people that say 4e has been designed from the other point of view first: The PCs encounter things that challenge them and you make a story up around that. Game first, story second, simulation third.
When I implement this idea it goes like this:
The PCs are 15th level, they are in Paragon tier so their adventures should revolve around issues that affect entire regions of the world. They should fight monsters around 12-18th level. An Elder Black Dragon is level 18 and the adventure might take a level or 2 to get to the point where they actually meet the dragon, I'll use one of those. He likely has a bunch of minions, they should be around the same level so that they are a challenge for the PCs. There are a bunch of Cyclops scattered from Level 16 through 18. They sound like worthy minions. The dragon maybe conquered them or made a deal with them to....search for an item he wanted. Now they are rampaging across the countryside destroying village after village looking for it. The PCs are called to deal with it. I don't want the encounters to get boring, so I won't use JUST Cyclops, they likely have some pets, some allies, and the PCs will randomly encounter other things(also around level 15) on their journey. And there we have the skeleton of an adventure. We then fill in the where and how and why. What village are the Cyclops attacking when the PCs confront them? How do the PCs hear about it? Why do the PCs want to stop them? Where does it go from there?
But if I was going for simulation first, I'd go about designing that adventure completely differently. After all, there probably aren't that many Cyclops around in my world, so a large number of them banding together wouldn't be realistic. The minions that the dragon could likely gather from the surrounding area would all be orcs. Which couldn't challenge the PCs at their current level. But I'll describe the orcs as attacking the PCs anyways, and describe them as being completely destroyed with no XP. Then, when the PCs finally convince an orc to tell them that a dragon asked them to do it, they'll likely attack the dragon's cave and the dragon will kill them since they got no XP from anything before this battle. But that's fair, the Dragon SHOULD kill them because they should be smart enough to know they can't just take on a DRAGON just because they are 15th level. And so the game likely ends in a TPK. Maybe they all get brought back to life and they start looking for a different problem that is closer to what they can handle, and so on.
Of course, I know my friends and I don't want to play in the second game.
