Previously I was using 1.3-beta6. In it, converting a layer to a tile map does not bring up a window.
For me, this was useful, because I could convert a layer, make some changes, and then change it back. I know this can be done via the tile mode, but I simply liked the fact that I could clearly see the type in the layers while making a change, to avoid confusion. When changing back it also remembers which tile mode you were in.
If that subjective use case is not enough, having a window come up is simply a bit inconvenient. There have been plenty of times where I want to quickly convert layers, and personally I’ve pretty much never used anything other than the default options. So the window coming up every time is just a bit clunky.