Believe it or not, some people think that Halo 4's Forge is bad. I, am one of those people. There are multiple problems, such as the block sizes, for example, the 4x4 corner, is not the same size as a regular 4x4. Here is a list that I've gathered of problems, if you feel I've left anything out, just comment below. But, this is completely a matter of opinion, if you disagree, do not take offense. These changes are also recommended for Halo 5.
1. The size of objects.
2. Take out piece limit. (Leaving budget.)
3. The size of the maps. Forge World 2.0?
4. The lighting. (Just tweaks.)
5. Zoom in edit mode.
6. Manual adjustments. (Pushing left stick in.)
7. Textures should be changed to forerunner style.
8. Gravity lift physics.
9. Piece design. (Coliseum window is rectangular.)
10. Missing pieces. (Glass sail.)
These things would most logically be added in Halo 5, however, some things could be added in an update to Halo 4.