When there are not enough items to fill a line completely, it is intentional to have a little space on the right, rather than justify the items or stretch the items:
- It does not look appropriate to fill the max-width when there are only one or two elements on a line. Then you have a huge amount of empty space in between the elements.
- Stretching a single (or a small number) element to the full width simply looks terrible and draws too much attention to that item.
We tried these options during the weeks of testing before tile layout was launched. This and other solutions to the problem do not look appealing and places undue emphasis on the last few items in the list.
If you have already modified the style of the tile layout where it looks okay to justify the elements on your installation and in the context of your wiki, then I invite you to make that customization. However, it does not work well on the default style of the tile layout.