When your motorcycle boots or shoes feel just a tad too big, a good insole can ensure a perfect fit. No two feet are alike.
From a foot hygiene point of view, an insole is also very interesting: changing the insoles of your motorcycle boots regularly is never a bad idea. Afterwards, your boots or shoes will feel all the fresher and better.
The inside and outside of a boot have to endure different things. While the outside still looks good and retains its watertightness, the inside can suffer greatly from frequent use. A (new) insole can be the perfect solution.
In any case: insoles are light, hygienic, replaceable, they absorb moisture and dry quickly, increase comfort ... many advantages for what at first glance seems to be an insignificant extra.