In Details view, the interface is clearly optimized for high information density and quick scanning. The small icon size supports this goal by allowing many files to be visible at once.
However, at this size, previews often provide little to no useful information. For example, PDF previews typically appear as indistinguishable white rectangles, and other formats are similarly hard to recognize visually. As a result, I frequently have to rely on file extensions to identify file types, which reduces the effectiveness of quick visual scanning.
In this context, file-type icons would be more informative than previews, as they allow immediate recognition without needing to read the extension column. The current behavior makes the Details view less efficient than it could be for managing large file lists.
This could also be extended to icons view if the icons go below a specific size threshold.