I did a search (as did the Microsoft Agent I discussed this issue with), but this suggestion doesn't appear to be here, which is surprising considering how many people used a bit of JavaScript that was on the Internet.

I would like CRM to let us set the default for the Activity Associated View. At the moment, it defaults to 30 days, but we would like it set to ALL.

There was a bit of unsupported JavaScript that resolved this before CRM 2015 Update 1 was released. It's at http://www.magnetismsolutions.com/blog/paul-nieuwelaars-blog/2013/01/11/default-activity-filter-on-to-all-dynamics-crm-2011-ur12

I noticed that quite a few sources on the Internet pointed at this script as a solution, so it appears to be a common issue.

I tried a fix for the script on one site, but it did not appear to work. It caused the Activities link to be unclickable.