To answer the original question
Seems like most alts now are just gimmick accounts.
As far as reasons for making them: (not that I support these reasons)
- before the redesign, we were able to change out user names, the alt serves as a nameholder so someone else doesn't take your original alias. This also being the reason why I made my alt, Sanjay.
- A way to get past the 4 posts per 30 minutes reply in a topic. Most notably used in sig threads or rating threads, which are often locked or deleted now
- To get around a ban while your main account is banned. Doing so and getting caught may result in a extended ban, permaban or even account deletion
- Gimmick / troll account, people will make these accounts to mock other users or to make a complete ass out of themselves, usually with the intention of getting banned
- And on a much lesser extent, some users may make an additional account for statistical purposes, such as a notable calendar date, to blam or protect only etc...
Now I will re-lock this as the discussion in this topic so far has been pretty lame minus a post or two.