I was editing system views for a customer today and had some issues with the company name field on the lead system views.
It seems that this is a bug which has been reported to Microsoft connect, so please upvote this. https://connect.microsoft.com/dynamicssuggestions/feedbackdetail/view/955886/cannot-add-company-name-column-in-existing-standard-view-in-lead-entity
I found this in CRM 2013 but it seems that it's an issue in CRM 2015 as well. Here's a thread where I found the connect issue; https://community.dynamics.com/crm/f/117/p/122564/405479#405479
Please vote on connect so we get rid of these mighty annoying bugs.
Developer at CRM-Konsulterna