Pros and cons of instance system. Thoughts on what should change?

I wanted to start a discussion on the instance system as it is now, as well as the proposed changes (personal instances). Here are a few questions:

1. What do you think the purpose of the instance system should be (how is it currently benefitting players, how SHOULD it benefit players?)
2. How are players abusing the current system?
3. What are some of the drawbacks of having instances tied to a guild/guild officers?
4. How would you design a personal instance system? What are the types of ways such a system could be abused?
5. How should the system work with alts, or players having multiple accounts or multiple 60s on the same account?
6. Do you foresee Velious content causing any issues with the current system?