You know when you go through a driveway at an angle and your whole dash creaks and flexes.Thats really bad for a car over and over. We dont have that.
In being more rare they will hold a higher value for longer.
Hardtop was mandatory when I bought my Supra.
Steve chime in here!
They are stiffer and lighter and generally rarer...those who are enthusiastic about them would not buy targa cars. I've owned 1 targa and 2 hardtops and it's noticeable (particularly on higher mileage cars). I do know of some low mileage targas that don't creak that much, but they likely will over time.
For those of us seeking high performance at all costs, the hardtop is the best overall starting point that Toyota provided.
Keep in mind that the real weight savings is chassis bracing, which I have no idea if or how you could easily remove. The roof itself is not the majority of the weight, it's this additional chassis bracing that the targas get. More investigation is likely needed.