I am with Tobias on all counts. If the pilot driving the thing is the F/O he will generally have a quicker reaction time to the command 'STOP' from the Captain, than is the case if the Captain has to assess, take control of steering etc and close throttles, apply wheelbrakes, select reverse, spoilers or whatever is appropriate. Also, in the case of the F/O handling the T/O and feeling something very obviously wrong with the controls or steering, there may not be time to communicate this feeling in suitable words to give the Captain the info he needs to take over. Up to V1 you may well get the very rare spurious abort with the concomitant costs, but how often really?
In training we seem to think only of engine failures or firewarnings, but what about jammed controls, unexplained buffetting, blown tyres (not necessarily a reason to abort, but training should cover this), multiple bird strikes, aquaplaning etc etc? When the Captain is flying, he can always make his own instant decision if it feels wrong, or heed the F/O's call, or choose to ignore it. The only difference when the F/O is flying is that he MUST react to the Captain's command to stop, and once maybe in his entire career he may make a wrong decision to abort....go back to my earlier comment above. As long as no one's hands are on the throttles after the V1 call, an over run would be a pretty rare event, and that is what training is all about. For those operators who always have the Captain hold the throttles for T/O, run some subtle incapicitation exercises and slow reaction exercises in the simulator and you will maybe see the wisdom of training for all scenarios and giving the levers to the F/O for his/her takeoff, ditto the nosewheel steering if it is fitted to the RHS and needed for the T/O. My current employer has the Captain take over the levers after initial thrust is set, and will never change, but that doesn't make it the best procedure, although in our operation it is safe enough. Fortunately our runways rarely put us right on the balanced field numbers and we never encounter slippery or very wet runways.