Re: Why hello there officer...
One isn't exclusive of the other. If they added a small battery bank that's recharged from the fuel cell, they could greatly improve that 0-60 time, and provide a higher top speed, if only for a short burst.
The fuel cell obviously puts out more power than is required for steady driving at legal (or normal) driving speeds outside of Germany, so it should be capable of always keeping the battery topped up. If you needed an extra burst for quick acceleration it would be available.
Realistically, in the market Toyota is targeting here, a 9.6 second 0-60 time is fine. That's faster than any cars I rent in Europe, and while on the slow side by American standards it isn't out of line for an economy car.