The change may seem subtle -- just an 8 pixels bigger tab. But that means the icon's surface doubles, which makes it much easier to notice/find in a crowded tab bar. And with two lines of text, a tab can fit most page titles (which are often up to 65 chars in length, since search engines index that much).
On the other hand, the change may seem drastic once you install the extension. If that happens to you, I suggest you keep using it for 2-3 days to get used to it. After that, you'll probably hate to go back.