20 years ago... German cars usually were heavier than Japanese cars. So, people said Japanese cars were too light!!!
Now Some Japanese cars are heavier than German cars. Then, people say Japanese cars are TOO HEAVY!!!
So, I think if you love Japanese cars, you should ignore those STUPID comments...
In my opinion, both heavy cars and light cars have their pros and cons. In fact, heavy cars are more stable and provide more premium GT ride on highway!!!
You also can put good aftermarket suspension such as Bilstein, KW, Ohlins and some decent tires, they can let your heavy full size sedan like GSF or M5 become as nimble as MX-5!!!