Realistically the reason for "excessive" alerts is probably just scope creep. The system almost definitely began as a mechanism to send alerts for really serious weather, but over time that definition's shifted, or they decided that sending more alerts was a good way to justify a bigger budget, or something similar.
There's been a number of lawsuits stemming around the Amber Alert system [1][2][3]. It's very plausible that they could find someone to sue for failing to issue an emergency alert. Not sure if they would win but it could encourage the NWS and local agencies to err on the side of caution.
FYI, you can opt out of these alerts: https://weather.com/news/news/2021-03-25-how-to-get-wireless...
Realistically the reason for "excessive" alerts is probably just scope creep. The system almost definitely began as a mechanism to send alerts for really serious weather, but over time that definition's shifted, or they decided that sending more alerts was a good way to justify a bigger budget, or something similar.