I really like the realistic buildings Menards has produced but fail to grasp the concept of selling new 'traditional' rolling stock in this hobby. Just look at most train shows and you will see hundreds if not thousands of Lionel, RK, Williams, and K-Line freight cars of virtually any roadname and size that has been produced since the 1970s still new in their boxes! Many of these cars have never been on a layout, never been played with or even displayed since being produced. You can still purchase and collect new Lionel MPC cars made in America for around $10 ea if you look - cheaper in bulk!
What is the appeal for a Menards freight car please?
First, any product that sells must have appeal (whether or not it can be put into words) to buyers and products that sell help keep the hobby alive if not growing.
Second, the last Menards house car I bought was closer to scale dimensions than most of the other/older products from K-Line, Lionel, and MTH RailKing. It seems close to some of the Williams offerings in scale dimensions (which I also like), most notably to me in the width where, IIRC, they are close to a scale 9-1/2' whereas most of the other cars are around 8 , 8-1/2, or 9' wide. I haven't bought a lot Menards cars but on the ones I have bought I like both the look and the feel that extra width provides.
Third, even with the hundreds or thousands that are already out there, maybe they haven't been done in a road or paint scheme that Menards has done that appeals to me.
Fourth, every Menards car has a unique road number so you can buy more than one car and not repeat car numbers. This is especially nice if you're doing a unit train or just like a large block of a single type of car.
Fifth, the prices are very reasonable and you get a new car with modern trucks, wheels, and couplers. If something has been around since the 1970s and it's new in the box, maybe there's a reason it hasn't sold. Menards products are more of a known quantity and with their great customer service there's less likely to be a hassle if there are any questions/issues/problems with the product.