Usually, when working with MoI, you want to get a mesh that accurately resembles the original file. So, if you design a sharp box, you get a box as output, not a soap stick.
And yes, building an arched window is done with just a few clicks. The only difference is that it's more of a 'destructive' approach, as the different boolean operations are not live.
Depending on the purpose, you might want to try two approaches. If it's 'just' a render mesh, n-gons driven by angle do a perfect job. I suggest using the .FBX format when dealing with n-gons to avoid reconstruction problems in most DCCs (.lwo is nice with Modo/Lightwave, though). Blender does surprisingly well using .obj, but it's an exception.
If you plan to add additional deformation or prepare a mesh for sculpting (remeshing), dicing the model evenly is the best choice, as you need accurate surface limits and can't rely on normals only.
They will both look the same in the viewport ...
But the evenly diced version can handle some advanced deformations.
MoI's mesher is simply the best, really. However, there is often a misunderstanding about what constitutes "good topology." Quad-only topology doesn't make much sense most of the time, especially if you are generating a render mesh. It's something you tend to stick to when doing pure poly-modeling or preparing a mesh for rig deformation (character work), as normals need to be re-evaluated on the fly in a surface
subdivision pipeline. On that matter, Groboto meshes will be a nightmare to work with anyway
