By default Piwik will create a new visit whenever a visitor views your website using a different campaign information from the visitor’s ongoing visit. You can disable this behavior by setting 1create_new_visit_when_campaign_changes=0
under[Tracker]` section in your config/config.ini.php file.
Proposal: set by default
create_new_visit_when_campaign_changes=0 in global.ini.php
Goal: this will prevent some possible confusion when many visits are created if links happen to include Piwik campaign parameters. By default, Piwik should be careful to create only one visit within 30 min period.
Kinda off topic: I wonder how to get more feedback on such important decisions. Since this will change the number of visits, which will affect many other metrics that depend on number of visits etc. Maybe we could post a very tiny blog post asking for feedback on this issue?