How to deal with students who refuse to do anything except take exams? This is a follow up to my previous question. Some context:

I teach at a new Fachhochschule-type institute, where my course is 5-day, 1 hour/day course to 20+ students.
I am actively teaching, providing the material, and encouraging the students to always ask questions.
My course is structured to have 4 days of lecture and 1 day of practical. In the practical, I explain a real-world problem and give the students graded exercises.

In week 1, the exercise in the practical was to prepare a half-page report on a short consultancy problem. I gave them 7 full days to write the report. No one asked questions or stated any concerns before the deadline.
The day after the deadline, only half the class had submitted on time, half of which only at minutes before said deadline. I was gobsmacked, since even half of the submitted results were very poorly made (one even stated, in the report, &quot;excuse me, but I didn't understand anything&quot;), by totally missing the point or even copy/pasting definitions without context from the lecture notes. In total 1/4 of the class actually proved that had sit down and worked actively on the practical.
The next day I explained that their actions were completely out of line, since in 6 months they are supposed to go in the workforce, and this behavior of completely ignoring and not giving notice to the professor would be very detrimental to their careers. I refused to evaluate any latecomer who did not advise me on time. My stern reaction did upset the students who didn't submit. I even received an 1-page email (double the size of the report) from one of the students claiming that my job is only to teach and their is only to take exams, and they are not obligated to do any extra work I give them.
Is there anything that I can do to improve the cooperativity of said students? Should I modify the final exam mark structure or organize the lectures differently? Since this is my first shot, I don't really know how to proceed.
Clarifications and Update:

It is technically true that the student's grades (according to university policy) are determined by exams only.
But, I am allowed to have practicals and other assignments count as part of the exam score. My mentor confirmed this.
I think these students are bad apples because they are clinging to this technicality rather than doing the useful assignments (or at least respectfully letting me know of their concerns in advance).
Based on the discussion here and with my mentor, I have decided to count the practical for extra credit only.
Welcome to higher education! Students will use formal assesement to guide their learning, and no amount of cajoling, or appealing to their sense professional or intellectual propriety will change that. Some students will always work above and beyond what the assessment requires of them, but most won't.
Assessment is how students comprehend what is the stated aim of a course. Instead of fighting against it, you might embrace it. For each learning outcome there should be an assessment that is aligned with that outcome - that is, it is impossible to successfully complete the assessment without have met the learning outcome. The learning activities are then designed to meet the outcomes. This might seem like &quot;teaching to the test&quot;, but in fact it is the opposite: in &quot;teaching to the test&quot;, the assessment defines learning outcomes, here the learning outcomes define the assessment. Biggs and Tang [1] refer to this as &quot;constructive alignment&quot;. [1] is a good read for the evidence that students have more or less always measured what they are supposed to learn by what they are assessed on.
Thus you would ask &quot;what learning outcome am I hoping my students achieve by this homework, and where is that assessed?&quot;. If the learning outcome isn't assessed anywhere, then it should be. If it doesn't meet a learning outcome then perhaps it shouldn't be set.
In practice we either make homework credit bearing (even if only a tiny percent of the overall credit), or, more frequently, ask an exam question that tests the learning outcome that a homework is aimed towards, and a student won't be able to answer without having done the homework. The final possibility is that the homework is practice for what will be tested in the exam. In this case you need to make this abundantly clear to the students. Even then, you will probably only get a fraction of the class doing it. The consolation is that this is the part of the class that deserves to do better in the exam and undoubtedly will.
[1] Biggs, J and Tang, C. (2011): Teaching for Quality Learning at University, (McGraw-Hill and Open University Press, Maidenhead)