I am interested in accessing more data on the karma of Lesswrong users without going to each user profile.

Between (1) the 15 all-time top users listed in the sidebar, (2) the 15 last-month top users listed in the sidebar, and (3) a few minutes' clicking on the usernames attached to recent posts and comments, it's hard to see that you're in danger of missing a lot of high-karma/high-profile users. How much value is there in what you're looking for, really? (If it isn't obviously trivial -- which I'm pretty sure it isn't -- then it's probably quite a lot of work to get more, because supporting LW isn't a very high priority for the people who do it.)

(If you've found that the posts you've found most interesting tend to be from high-profile users, that suggests that your preferences match fairly well with those of the LW community as expressed through karma, which in turn suggests that you can probably find promising articles to harvest promising usernames from just by running through the recent-articles list and picking out ones with high scores.)

Note, though, that any process that uses karma to select which users or articles you'll investigate further may introduce a selection bias that will corrupt your estimates of the relationship between karma and interest-to-you.