Believe me, I'm not one to defend engineers.
But, I do have family, and friends, that are engineers. (At least they are not lawyers). Guess who they call, whenever they need a problem solved with their own stuff?
However, many issues people rant over, are not actually the fault of the engineering department.
An engineer can easily design it, to include all the things that would make it easy to service, or even make it so it won't need to be serviced at all.
But, every part has a budget attached to it. Go over that figure, and, the budget department will reject it. Convince them, they have to increase the budget for that part, and they will expect someone to cut the budget on something else to pay for it. They may force engineering to have no option, but to use an existing part. And, refuse to allow engineering the money to make the changes, that would make a part more accessible in that application. Leaving to you, wondering why the engineers were so, "dumb"?
So, while it may seem like penny pinching, it all adds up when you have many hundreds of parts, and a budget that has to be met.