Thing is you'll never convince people, who've been stung, otherwise. And likewise I'll probably not change my opinion unless I get a succession of poor french cars. I'll keep trying.
What you need to remember is that sure, they may be cheaper and less well put together, but they cost a lot less, cost less to repair (especially if you do it yourself and are only buying parts) and tend to be lighter and more economical.
At the same time as I bought my recent 306 estate my brother bought a BMW 330D for 4x the price and 5 years newer, with full BMW service history. In that time I've had a crank pulley (caught early, really only replaced "just in case") and a wheel bearing (caused by a pothole impact).
He's had a new window motor, a new injector, new MAF, 3 trips to the dealer for MILs, a full new set of suspension bushes for the rear, a full new set of shocks all round and has had to glue and pin his intake manifold back together himself. It's a nice car, but I'd have expected better TBH. Amazing car, lovely and comfortable, grips like glue, goes like stink but by god has it cost him.