Because they couldn't design a good one?

Having worked on them for years the Windstars were the biggest POS ever made in that market. They really are a pile. The Aerostar was ok but decidedly under powered and a bear to work on. If they'd have put the 4.0 in the Windstar rather than the 3.8 they might have been ok. That 3.8 would blow a head gasket in a heart beat for no apparent reason.

No one makes a better minivan than Dodge period. Early models had there problems, mostly in the trans but they've been pretty stable the last 10-12 years.

Toyota Previa van is the worst designed van on the planet. Mid engine in a van is stupid from every angle. The Sienna is nice.

The GM vans are nice but they seem to start falling apart at 100k, I know I have 2 of them. Both bought cheap with blown head gaskets due to customers ignoring the leaking intakes. Talk about rattles yikes. I do love the way they ride but the fit and finish lacks.

Nissan? Forget it.

For the record I own a 2002 Dodge Caravan from new to 250k on it now, it's the latest in a string of 4 we've owned. We will be replacing it with another Caravan soon. At 250k it still rides and runs like new without the rattles one would expect at that mileage. It is destined to become my main 2x2 Hauler.

I use the GM minivans for customer loaner cars and one has the rear seats removed and stored away that I bring home on the weekends for flying field trips. Once the wife gets her new one the seats will go back into the Pontiac and live it's life out with a bunch of strange screaming kids crawling in and out of it. Poor van.

Tim