Bidding on branded terms give the advertiser much more control over the visitor’s journey. This is true for any paid campaign and includes both the pages they land on and the route they take through your website.
Branded SEM allows you to reduce the possibility of a competitor or another site capturing the visitor and creating a negative brand experience (BBB, Ripoff Report), or going to a competitor (competitive branded bidding and review sites).
Branded SEM lets you serve variations of websites and landing pages without sacrificing as many conversions as you would via none branded SEM. Why? Branded traffic is less likely to allow tested conversion elements to detract them from making a purchase or filling out a form