Question

Why is scale important in a map

Answer 1

Map scale refers to the relationship (or ratio) between distance on a map and the corresponding distance on the ground. For example, on a 1:100000scale map, 1cm on the map equals 1km on the ground.

Answer 2

Scale is one of key element of a map, when one create a map, a scale is must, having coordinates would help but many times this is not shown but scale is must.
Now let me tell you why it is important.
As you understand maps are scaled down version of the world, I can draw entire country map on an A4 sheet and on the same A4 sheet I can draw a state, district, city or a village map, now how do I represent how big these administrative blocks are? for this purpose I need a scale.
On a village map 1cm may be equal to 50m
The same 1cm scale on country map would be equal to 50km
If you want to tell this aspect of map to the audience then scale is important.