These 6000i and 270D machines that I have are now over 3-1/2 and 5 years old, and I sew on them daily. I have made many quilts including bed size as well as wallhangings on them, and embroidered several hundreds of projects. And have toted these machines along to class and sew-dates too often to count.
Time has not shown a decrease in the function of these machines.
I also have a Bernina 440QEE, and the Brothers have stood up just as well, with actually far more use than the Bernina. If I damage the Bernina, or if it needs servicing, I'm out a whole lot more money than would be the case for the "smaller" machines. Which are smaller of course, and a lot less monstrous to carry around.
I keep the machines clean, and have no plans to "trade up" because everything I've wanted to sew has been accomplished on these lighter-weight, lighter-class machines.
I guess they could be seen as disposable, because if I threw away all the ones I have now and replaced them all with new ones of same brand, I would still not spend what one "cadillac" sewing machine would cost, nevermind trying to buy all the extra feet and attachments for the expensive machine.