As an engineer I want to reuse and expand and not throw anything away.
If you were truly an engineer (a real one, not just someone with an overinflated title), you'd know that things age and wear out.
NASA can't build tin cans that can survive in space for a hundred years? There are planes from WW2 that are still flying and those rattle.
A real engineer grasps the impact of parts count and complexity. Not only is the ISS not just a "tin can", those planes are orders of magnitude simpler than the ISS.
Not to mention that those planes take hundreds of man hours a year to maintain in flyable condition - and man hours in space cost tens of thousands per.
Things get at least a hundred times cheaper when they don't have to survive the stresses of liftoff.
Sure, as any engineer knows, you can easily manufacture things given enough infrastructure. Since you're an "engineer", you should be able to estimate the cost of developing a (currently non existent) weightless capable factory complex, and the costs of placing hundreds to thousands of tons on orbit, and the ongoing costs of logistics, support, and maintenance needed to produce those "hundreds of times cheaper" parts. You'll also be able to understand that a space craft is made of hundreds of different kinds of materials, only a few of which are amenable to recycling.