This directly relates to: BluSunrize/ImmersiveEngineering#3813

First of: I didn't tried this mod yet - my knowledge only come from 2 YT videos.

As I'm really into all those fancy steampunk-ish mods with all those in-world stuff (in contrast to e.g. IC2 with only 1 Block black magic machines) but also prefer to have a rather peaceful playstyle I noticed that Create like Immersive Engineering is gated behind going to the Nether and get some Blaze Rods.

Don't get me wrong, I myself am cool with this, but as I also have some friends like to play in peaceful only from time to time it would increase the difficulty to get Brass by quite a lot. If one plays in peaceful the only way to obtain Blaze Rods is to find them as luck based loot in Chests. make it impossible to get Brass (source: https://minecraft.gamepedia.com/Tutorials/Gathering_resources_on_peaceful_difficulty#Blaze_Rods). So, without any additional mod enable to get Blaze Rods/Powder in peaceful sadly using Create would be end pretty early before one could get really started.

Do you may consider to add another way to obtain Brass in peaceful?

If you really want something like that you can make a datapack to edit or add recipes that would allow for peaceful play. Like instead of Blaze Rods or Blaze Powder, you could change it to netherwart, glowstone, and many other things. Just a thought, but a "Peaceful mode" probably won't become a real thing.