In what manner? Other than the exhaust welds name one issue that has anything to do with build quality? In fact the concensus is that they construction quality is extremely high. And shall we mention the $1,000 you need to spend on the W124 every few years to replace with wiring harness that dissolves? Or the 6 cylinder diesel engine that won't last 100k miles? Or ....

The problems except for the cat welds all fall into the bad engineering category. And most of the bad engineering was fixed early on. Once the W123 gets past the 60k mile "break in" where all of the problems occur if they were fixed correctly none of the expensive issues have a history of returning. The ongoing maintenance can be excessive but tend to be very cheap and easy fixes such as the brake light switch or the CkPS.

Now if you choose to take your vehicle to a dishonest repair shop of course you can wind up spending a lot of money in unnecessary repairs. But this is true of any vehicle.

One issue that should be stressed though is that you are looking at a completely different animal than your light sedan. This is not even the same unibody oversized cars that are called SUVs. This is a light truck designed for moderately severe off road use. Even with the 4 wheel independent suspension and no axles it is going to ride like, well, an off road truck. Handling and ride comfort is superb for a truck but still truck-like.