I'm here to learn languages, but the value of Italki to me is that COMMUNICATION with a live human is a strong motivating factor.
As a teacher, I'm very familiar with students not seeing the point of learning a vocab word or a grammar issue. However, when you want to understand someone and want to communicate with someone, it gives meaning and weight to the language skills. People like to express opinions (see Facebook/Twitter/etc), and so you can hijack that desire in a pedagogically useful way.
So I like asking my teachers and language exchange partners on Italki questions about their lives, and communicating what I did over the week. And talking about our problems, opinions, and values. It's not "friendship", perhaps, but it's personal communication and it's community in a way. Odysseus went out to see many cities and minds of many peoples, and I think a lot of people on Italki are learning languages in the same spirit.
You completely right it looks like so many people here are not really interested in learning languages, but to meet a soulmate. Also, probably, some people from societies with gender separation look for an option to have a chat with the opposite gender. Probably for us, who have a wife/husband, it is difficult to understand what all these people are doing here. Probably they so young that they hesitate to register on dating sites. I don't know, those are just my assumptions.
On the other hand, a student needs to practice a lot. And it is not possible to have a teacher/tutor for several hours every day, so it is good to have somebody to speak to your target language. You know many language schools encourage students to speak the target language with other students. Without some kind of friendship, it is impossible to have a language partner for a long time.