In response to the rising tide of content-theft and ongoing griefing: implement a 3-tiered access system for Second Life. It's vital SL remains open and free-to-access BUT there should be strict limitations on what unverified* accounts can do whilst inworld. A 3-tiered access model is easy to understand - it's how the web works now - and could, with a single stroke, make a huge difference to the security of content and levels of griefing in SL.
Tier 1 : Unverified* Free Accounts - would get free access to SL but would have NO build, rez, upload, download or scripting facilities anywhere. They can still customise their avatar with skins, clothes and attachments but cannot rez anything inworld or create content.
Tier 2 : Verified* Free Accounts - would be as now, able to build and create anywhere inworld they have the appropriate perm's.
Tier 3 : Premium Accounts - would be as now, able to build and create but with added features (hopefully more than now)
This access system would keep SL open, allowing anyone to visit and explore Second Life at any time BUT would prevent anonymous accounts from many forms of griefing and would deny them the tools needed to redistribute stolen content. If a verified account was to steal or redistribute stolen content then it can be traced back to a RL person and appropriate action could be taken. We can never stop all theft or griefing in SL but we can implement the major disincentive - the threat of capture - which barely exists now.
It could be argued that unverified accounts need basic tools - for adjusting attachments for example, but these adjustments (such as Scale and nudging) could be scripted into attachments to make things easier. It might be argued that these limitations will kill creativity in SL, but since all you need supply is basic verification (like a credit card number) to get full build facilities it seems unlikely and after all if you can't supply such basic verification maybe you shouldn't be in SL anyway?
*For the purposes of this explanation I assume 'verified' to mean verified with payment information. IMO the proposed Age-Verification is a bit ridiculous and doomed to fail. If a credit card number is enough verification for Linden to take our money or, on the web, to get us access to the most explicit porn then it's enough verification for us to see nude avatars in SL!