Last week Twitter underwent one of the biggest redesigns in its seven-year history, but you’d be forgiven for missing it. Embedded images and video are now displayed automatically in the updates you see, instead of requiring a click to expand and view. Buttons for “retweeting,” “replying,” and “favoriting” tweets were also brought to the surface, cutting in half the number of clicks needed to interact with a tweet.

Which is not to say the changes are insignificant. Indeed, they are a sign of things to come, as Twitter tries to balance its simple appeal and the demands of its users with a growing need to make money.

As Twitter nears its IPO, the new presence of images and videos may help woo people currently using Instagram, Snapchat, or other rapidly growing social photo-sharing services. They certainly make Twitter more appealing to advertisers: previously users would have to click on a promoted tweet to see an image; now it’s in your face. (After the update, some people joked that Twitter just launched banner ads.) The newly prominent social buttons will also encourage more interaction, making it easier for Twitter’s many lurkers to engage, and lowering the threshold for tweets to go viral.

Twitter has been signaling for some time that a more radical redesign is imminent. As a soon-to-be publicly traded company, it needs to increase users, and one way to do that would be to find a way of diminishing the number of people who sign up for Twitter, can’t figure out what to do with it, and never come back. Last month a Reuters/Ipsos poll found that 36 percent of people who joined Twitter say they don’t use it, citing a lack of friends on Twitter, and confusion over how to use it and what it was for, among other reasons. In comparison, only 7 percent of Facebook members say they don’t use the site after signing up. Possibly the rumored television stream—a separate column for people discussing television shows, and for broadcasters to promote shows, and for companies to place ads across both screens—could serve this purpose without disrupting the main feed. And possibly Twitter could continue its attempts to recommend content it thinks people will be interested in, carrying on the work of the neglected Discover tab—a personalized stream of top stories and tweets that will reportedly be cut—in some other form.

But the Discover column’s neglect indicates an important challenge for Twitter. Its users are reluctant to take too much heavy guidance, and they have the perfect venue for venting their displeasure if they disagree with changes. Even the minor addition of blue lines to sort Twitter conversations into groups elicited a backlash, though that appears to have faded. Twitter is also driven disproportionately by the activity of a small coterie of power users, some of whom have several million followers.

Twitter’s light touch with redesigns shows that it knows this. The challenge will be keeping this in mind going into the IPO—as pressure to make money inevitably increases.

In contrast to Twitter, Facebook has undergone major overhauls of its user interface several times, each of them usually accompanied by howls of outrage and petitions (on Facebook) to roll them back. Twitter looks extremely similar to when it launched in 2006. Many of Twitter’s redesigns amounted to adjusting its interface and features to better accommodate things its users are already doing, rather than foisting new features upon them. Some of Twitter’s most iconic features, like the hashtag and retweet, were first created by users before Twitter built them into the architecture of the site.

“Facebook tends to build what they want for their users rather than listening to users and building what they want,” says Brian Blau, an analyst who covers Twitter for Gartner—“not that one is good or bad.” He attributes the difference partly to the two sites’ different goals: “Facebook has much broader ambitions, to connect the world, and when you say that you can think about different ways of connecting people—the wall, timeline, news feed. You can change the user interface, and people may not like it, but they like being on Facebook so they tolerate it, and now they don’t remember.” Facebook, it’s worth pointing out, is more embedded in users’ real-world social lives, making it harder to quit or ignore.

Twitter, he says, has stayed very focused on a single pillar: real-time, short-form communication. It has kept its focus even though Twitter’s original constraint, the 140-character limit, was a limit imposed by the SMS texting the site originally used, and no longer applies.

“Twitter’s beauty is its simplicity and its creativity is its constraint, 140 characters,” says S. Shyam Sundar, the founder of the Media Effects Research Laboratory at Penn State. When your form is your function, Sundar says, it creates certain constraints when it comes to redesigns. You can add videos and images and shortened links to tweets, but if you touch the format of short messages presented in a reverse-chronological stream, Twitter won’t be Twitter.

So far, when Twitter has made design tweaks, it has tended toward giving users greater latitude in how they use the site rather than directing them how to use it (as Facebook might do). When the first Twitter users signed on, the site prompted them with the question, “What are you doing?” As Twitter moved from a microblogging platform often mocked for its mundanity to a place where people posted about news and events, that injunction was swapped out for the more open ended, “What’s happening?” Today it’s simply, “Compose a new tweet.”

As people started using Twitter as a way to share and discover hyperlinks to interesting content as much as a blogging platform, Twitter accommodated them, developing its own URL shortening service. After images became one of Twitter’s major functions—the twitpic of the plane that crash-landed in the Hudson River was a turning point—it decided to host its own photos. Even the “trending topic” chart in the margin, a major new feature in 2009, simply gave a more prominent location to information about what was already happening on Twitter.

So far Twitter has stayed remarkably dedicated to its original interface, taking a hands-off approach to how its 230 million users want to use it. But it will soon have another powerful bunch of people—investors—who also want to be heard.