On most sites the title of a question is self explanatory. However, on a specific subset of sites (gaming and boardgames and other game-related sites, primarily) the first/only/primary tag is integral to describing the question.
On all sites, /questions lists tags below the question title, which is helpful. On the question page itself the first tag is shown in the page title (a matter of SEO, originally), which is helpful on some platforms. However, most other places that link to questions don't show the tag. This includes the live feed on http://stackexchange.com/, user pages, the Similar Questions list, the "Questions that may already have your answer" list, etc.
In a lot of these contexts it would be helpful to see the tag, but only on some sites. Could we, should we, be able to see that tag in more places?
EDIT: For example, on gaming.stackexchange.com, asking a question like "Where can I find the first sword?" makes perfect sense if you see the tagged game, but is a rather vague and worthless title without. Also, if that question has already been asked about one game, and I try to ask it about another game, I will see it in the list of previously asked questions, and waste time checking if it's relevant.