1) VW is building a car to compete in the American midsize segment. If you want to be competitive, then your requirements for upkeep need to be competitive. But their's are not.
2) Stuff breaks. Just because you had to replace one doesn't mean it is a common issue.
3) Brake fluid is hydroscopic but there needs to be a way for the water to enter. Most modern systems are fairly well-sealed. Also, just because the fluid contains moisture does not mean it needs to be condemned. The boiling point may still be adequate for the anticipated use and the corrosion inhibitors could still be sufficient.
This article is a bit dated but the principles remain the same. The info is from the Big 3:
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BRAKE FLUID -- Ford does not recommend changing DOT 3 fluid or flushing the system. Ford says their recommendation is a "risk versus benefit" assessment because there's a potential for doing more damage than good. If sediment or contamination from the master cylinder is pushed through the ABS unit, it can cause big problems. Flushing the system also increases the risk of air entrapment and leaks, says Ford.
Ford says their brake systems are engineered to tolerate brake fluid contamination of up to 3 percent moisture without fluid boil (which is close to the saturation point for DOT 3 brake fluid). If the fluid has more moisture, it probably has some liquid water in it and should be changed.
Ford said they measured the water content in 7 to 10 year old Ford vehicles and found that the water content was actually quite low: only 1 to 1-1/2 percent. So based on their findings and the design target of 3 percent water, they see no need to change the fluid for preventive maintenance.
Does pushing the caliper pistons in when changing the pads push contaminants from the calipers back toward the ABS unit or master cylinder? Ford says no. There's not enough movement or migration to cause a problem."
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With the exception of Viper, all current domestic Chrysler products use high temperature DOW 1000 DOT 3 brake fluid, which has a boiling temperature of 550 degrees F and surpasses the government's minimum performance requirements for DOT 3 brake fluid. Chrysler says their fluid can absorb up to 3 percent water and still meet the DOT 3 specifications for boiling temperature. Consequently, they see no reason to change the fluid for preventive maintenance.
In the past, European brake systems used vented master cylinder caps and lower quality hose and seal materials which allowed moisture to contaminate the fluid relatively quickly. Because of this, the brake fluid had to be changed periodically. But this is no longer true. Most European and domestic vehicles use sealed master cylinders with EPDM hoses and seals that resist moisture penetration. So fluid changes are a thing of the past, Chrysler says."
https://www.aa1car.com/library/procut3b.htm
