My 2015 (non Hybrid, 350) also has a stiff steering, to a point where the wife refuses to drive the car! Took it to the dealer (twice) and was told there's absolutely nothing wrong, it's within spec, and certain vehicles just have a tighter steering over others!

 

Are the front tire pressures ok?

 

Im not buyin that... That just sounds like a load of BS to me.

 

 

I know... I hate going to the dealership or to a new mechanic that I don't know, but I think that's what you should do.
People have so much faith in Lexus and when they go to a Lexus dealership they forget they aren't actually dealing with lexus. A Lexus dealership is just like any other independent mechanic shop you would walk into. Every mechanic and every shop is different, so treat the dealership just like you would any independent mechanic, and don't think that they are somehow "Lexus". They have just made arrangements to sell that brand of cars... That's it.
Just because a jewelry store is an authorized seller of Rolex, doesn't mean that jewelry store is operated by Rolex. Yes, Rolex will give the store owner some guidelines and keep them updated on their products, but in the end it is still just some random person that owns the store and who filled out a form, asking Rolex if they could sell their products.
My point is, don't confuse the dealerships that are authorized to sell Lexus cars with Lexus Inc.. Treat the advice they give u the same as you would a random independent mechanic, and get a second opinion if something doesn't seem right.