Because the internal logic they gave is that objects going faster than light go back in time 'according to Einstein'. That's obviously complete nonsense as you would have to have negative mass- they can sci-fi gibberish it all they like of course, but then it is a sheer lie to say Einstein had anything to do with it.
That same internal logic showed- when it first happened to her- that she did not move back to where she left; she had to go forwards in time the normal way, one second at a time.
They have not said tha Daphne's ability now extends to time travel; it is still just speed. They have just said that enough speed moves you backwards in time. That leaves no mechanism to move forwards in time any faster than normal.
This is not just nitpicking- it is a directly internal continuity issue which, along with the 'why is Arthur Petrelli dead?' issues and many others is part of why Heroes is aggravating to a dedicated fan. Make up any old nonsense you like- men are flying after all- but it has to make sense within itself, else it's just random and no-one can build a sense of coherency.
I enjoyed this volume, but I got lost in all the logic I guess with formulas and catalysts (still don't get how Hiro's mom got the catalyst, but I digress).
A couple of things:
Now, Matt and Daphne touched upon the idea of them recieving powers that they wanted. How when the eclispe first occured how Matt wanted to hear others thoughts and how Daphne wanted to walk and now she has super speed. They said this in reference to Ando (is that his name?) getting time traveling abilities. I thought this was kind of interesting, but what through me was when Peter injected himself with the formula, he got the flying power. Are they suggesting that this is the power that Peter really wanted?
Peter was an empathic person and received empathic mimicry when he injected himself. He absorbed it from Nathan.
I'm not sure if the 'I'm like this so I got this power' thing holds true for everyone, but maybe a bit. Daphne gave examples of Matt always wondering what people thought of him and getting telepathy, Daphne wanting to move and getting to run super fats. Peter was a caring, empathic person and he got mimicry. Ando always played sidekick to Hiro and so can super-charge other people's powers.
What about the others?