In context, it's talking about sprites that are going to get non-integer scaled anyway (in-game pickups), so it's just about maintaining a consistent detail level. If those specific sprites had their resolution increased, everything else would need its resolution increased to match them.

Inconsistent resolution isn't necessarily a bad thing, e.g. Elite for the BBC Micro changes video mode part way down the screen so it can display both high resolution monochrome wireframe 3D and a lower resolution color map/UI below, but it's not idiomatic to the MS-DOS style this game is going for.