Hi Selos,
There are a couple of reasons to understand why Pivots are set to the World Origin: Modular design and working on the grid. You’ve got the idea of thinking modularly down and you have a understanding of Lightmaps which is fantastic!
When you export from your modeling software, in this case 3Ds max which I use as well, you understand that the world position there will be the pivot of your mesh when you import into UE4. It will not retain the pivot that you set up for your mesh in Max. There has been a feature request to have the FBX import keep the original pivots that were set by the user in their modeling software but there is no timeline of when/if this will be implemented.
Since the point here is modularity you want to have your meshes pivot placed at the world origin of 0,0,0. It’s recommended that if you’re doing a wall, for example, the pivot would be in one of the bottom corners. When you export you would then set all the meshes pivots to move to the world origin for import into UE4.
You end up with this result which allows you to build your level with your modular pieces you can use over and over:
The other option is to leave all your meshes where they are in Max and export. Make sure to not check “combine meshes” option when importing though. This will still give you all your individual pieces but you will have one pivot point location that works for all your meshes. When you place them they will be offset by this but they will be properly placed. This may work if you’re not intending on using them for any other purpose than that.
Three Meshes with the same pivot location but different offsets:
The idea here is that when using modularity you’ll build your mesh assets in your modeling software and assemble and build your level in UE4.
I hope this helps and feel free to ask any questions if I’ve been confusing or what not.
Thank you!
Tim