This post is more retrospectively: The week before vacations, I listened to some talks students gave as the last step of their Bachelor (BA) thesis. I had read the theses of the three students I co-supervised and the talks where quite OK: Students could show what they did, how and why, and they answered all questions properly. It was organized a bit like a thesis defense: Supervisors are supposed to ask first and then everybody else can pose a question. The audience is the lecturer responsible for this event, the supervisor(s), and the other BA students who already had presented or will present later. As I understood, there was a course running the whole semester where students discussed how to present their theses.
This "defense" is not part of the official procedure, it doesn't influence the grade. But as supervisor, I liked it a lot -- I could see other students and get to know about the topics they had been working on, and I could very easily test if "my" students really had been working on their topics on their own, and if they really understood what they had written down. I'm not sure if the students liked this part of their BA thesis, but I hope so -- it's the only possibility to tell a bigger audience about the work of the last weeks that had absorbed all your energy. There are only two people who ever read the thesis paper (the supervisors), but here are 10 or 15 people listening to what you discovered and what you think about related work.
The BA is a proper final degree, so students could leave university and start the real life with a real job. Studying linguistics, i.e., something from the humanities, your degree basically says that you learned to read, think, and write. Therefore you should have written a longer text (ca. 50 pages) and spent quite some time researching and thinking. That's what your thesis proofs.
However, not every BA in the humanities requires writing a thesis. At the German Department in Basel, students have to write two term papers (ca. 20 to 25 pages each). Topics could be related, but don't have to. So this is not a "longer text", and students don't invest that much time and energy. I don't consider this a good solution. A the Faculty of Humanities and Arts in Zurich, the first version of the BA regulations had no specific demands with respect to a thesis -- depending on the courses students choose, it was even possible to obtain a BA degree in the humanities without having been writing a single term paper ever. Regulations for seminars afforded getting credits by giving a talk only. They changed this now, but a proper BA thesis would be an even better idea, I suppose.
Of course, in the Swiss Bologna implementation, the MA degree is the "proper final degree." and towards your MA degree, you have to write an MA thesis. But first surveys show that indeed, students leave university after having completed their BA and maybe or maybe not return later for doing an MA. As there is no long final written or oral exam for the BA study as a whole -- students just collect credits during terms -- the BA thesis is the only possibility where students can show that they not only acquired snippets of knowledge and single competencies, but that they are able to combine everything they learned and solve a bigger task -- and write a longish text.