This is too easily said and subjective imo. My car came with such UHP tires (Bridgestone Potenza Sport) and thought the same as you. I then switched to CC2 and the driving pleasure was gone although previously i had got good experiences on such tire on a front wheel drive Lexus (ct200h).
Now I am on the Goodyears (Assymetric 6) and i am happy again. This tire is quiet, comfortable, holds the road really well and is also a fairly good rain tire. Is also a reasonably affordable in purchase (<100€) and fuel economy.
I am not a racer but I do value good cornering, straight line stability and an allround stable tire.
Considering the IS300h is a heavy car with relatively soft suspension, I do believe the car benefits from a tire that isn't too soft in its construction. But like I said, it's subjective. My out of the box experience was an UHP tire when I bought it and I stuck with it.
In finding the right tire after the CC2 misery, I found the TireReviews youtube channel and website useful.