The 200 was launched in the UK to take on the BMW 316-318-320, Audi A4 2.0 and Mercedes C class.
They fitted the 2.0 because the market in Europe don't want bigger engines that cost more to tax and return poor mpg.
For the market the IS200 was aimed at the power is right, it's not a fast car and was never meant to be. It's a comfortable cruiser.
I'm also pretty sure that they putting in a tuneable engine didn't even enter their mind, why would it? They weren't trying to sell cars to the performance market, but to the corporate business market.
The suspension is high because again they were selling a comfortable cruiser not a fast sporty car that's slammed but one that comfortably eats up motorway miles. So yes they did know what they were doing