ID can be very technical/engineering related…but it also can be more towards the artsy/trendy brand side of it.
You can also be a stylist but unless you have a strong mechanically oriented ID team it will remain a concept.
If you also have to interact with Engineers and your answer is I don’t know how it’s made…then the engineer will “design” it for you.
The 3 examples you gave are very different.
Yes the laptop bag is very simple but I can assure you it didn’t magically appear from a sketch. The designers (even if not by degree) probably had to get very technical and learn everything about making a bag. From hardware to fabric to sewing to sourcing and so on.
The boxed water is a smart concept. The designers probably had to get very technical and learn a lot about the beverage distribution business. The challenges of shipping so many empty containers and the wasted space of a circle vs a box. Also, they probably had to learn about the pros and cons of a plastic bottle vs a cardboard box with a special inner lining and how it affects taste over time.
Modular homes and capsule hotels. How would you design it if you have no technical or engineering knowledge? Structural loads, shipping challenges, collapsible or modular structures, building codes, durable materials, cost, life of product, plumbing and electricity, serviceability, different weathers/regions, ergonomics, appeal, etc. It goes back to if you don’t have a good technical background then you’ll be relying on somebody else telling you what can and can’t be done. Sure you can designed it but if it’s not manufactured then it will remain a concept…there’s a lot of them out there. You don’t need to be an engineer and designer but you need to know enough to present some viable concepts.
Part of being an Industrial Designer is being inquisitive and learning different things. If you don’t like engineering then don’t go into industrial or structural products. But if you choose softgoods, consumer electronics, home décor, toys, shoes, or any other product you must be willing to learn the technical details of the materials and processes used in that industry.