First I will preface this by saying it is of my opinion that modernizing TWCs links would be very simple as it mainly concerns the header & html code which anyone who has 30 minutes to spare can understand. But perhaps Gigantus or somebody else can chime in if this isn't the case.
I intend to highlight several things I consider problems that adversely affect the site in subtle ways.
Users often describe mods as the life blood of TWC and most english speaking people read from left to right.
On TWC's home page we have several links:
Home - Wiki - Store - Forums - Downloads
Consider again how most people read, and yet Store, an entirely non-functioning link is listed directly after the Wiki.
Now consider the way Steam Workshop presents itself, Steam allows people to download whatever mod they want after immediately presenting them with that option.
What does it do specifically?
a) Steam immediately presents several downloads to the user
b) It has a single link that immediately allows them to browse the download section
This can't be done in the same way on TWC, obviously we like to direct people every which way and bombard them with content which leads to information overload. But! That's ok.
Perhaps we can simply remove the non-functioning link to the store and replace it with Downloads or the Forums.
Now let's take a look at the links on the forum we are now at the top. Where exactly is Downloads located?
Links in order from left to right:
Home - Articles - What's New? - Forum - Competitions - Blogs - Rules - FAQ - Wiki - Awards - Downloads
To be precise, it is located in the 11th position, Directly at the very end.
Let's think about demographics, most commonly active users are in the age range of around ages 12 to 65 but heavily clustered around 12 to 25 based on a random sample of users with their ages shown.
This age range isn't likely to have a large attention span and reading left to right leaves them unlikely to see the last item unless they're very interested in whats on the end.
Ok, what do you say, steam is a different platform?
Fair enough, lets look at Nexus Mods. A very famous site for TES & skyrim modding. How do they structure their links? Incidentally they have two ways.
Their primary links are:
Game - Mods - Images - Videos - Updates - Support
With a secondary one above it and pushed to the middle right
Nexus Home - Forums - Chat - News
I'd suggest we take a long and serious look at how these things are structured as they play a very important role in retaining guests and turning them into members.
Nexus currently follows a rule where they allow a download to be visible to a guest but alert them that they can only download files under a certain size (something like 1MB).
We used to hide download links that were attached to the site from guests. I'm uncertain if that is still the case but if it is -- then it might be a good idea to let them know that they can't see the link until they register or simply limit which files they are allowed to download by size while still showing them it, and then alert them to the fact that they need to register.