I'm not sure I've ever seen a softside suitcase with a stiff plastic lining.
I buy name-brand luggage, but I don't pay a whole lot for it. I buy it at places like Tuesday Morning, TJMaxx and Marshall's. So far I've only had one really break; a wheel somehow separated into concentric rings, on a Ryanair flight between Dublin and Stansted. I was dealing with the baby and I didn't notice it b/c DH was wrangling the luggage to the car, and he didn't tell me the wheel was malfunctioning until we were well out of the airport. I got new wheels put on at a luggage repair shop for $20, and the bag is still going strong 6 years later.
I did have my Prince Lionheart carseat satchel get chewed up by bagroom equipment once -- that was on a FlyBE flight from Belfast to Leeds, and the airline insisted on giving me 50 pounds Sterling for the damage, even though the bag only cost $30 to begin with. I caught my connecting flight back to the US, bought a $5 vinyl repair kit at AutoZone, and I'm still using the satchel 10 years later.
I do make sure that the frame in my softside baggage is metal. It bends in, but it is easy to straighten back out if you put your foot on the inside and pull up.
I just replaced two of my pieces that had begun to really wear out, after I don't know how many flights. (Frayed fabric on the edges, zippers that were missing teeth, handles that tended to stick, etc.) We bought them both 19 years ago, the year we got married. One was a TravelPro, and the other was an Amelia Earhart.
So ... I'm here to tell you that it is possible to get a very long life out of luggage that didn't really cost a lot. I'm not in Bavaria's travel league, but I do fly rather a lot.