Would you say that vulnerability with CVSS score that points to low is equally important to verify and take care of than CVSS which points to critical?
The most boring reason, even if you take CVSS scores at face value, is that in many cases it is possible to leverage multiple "low" severity vulnerabilities into a massive impact.
But the bigger reason is that CVSS scores are all over the place, and the people operating roulette wheel that generates them do not have any insight into any specific person's systems.