By abolishing it at the national level you remove the rights of the states to make laws for themselves that are not enumerated in the constitution. (Me, I'm a right to life, liberty and the pursuit of happiness guy)
By having Roe V. Wade overturned the rights revert to the state level.
The Republican Party itself will not abolish Roe v Wade. Any and all Roe v Wade talk after an election takes place embarrasses the Republican Party. The only time the Republican Party wants to talk about Roe v Wade is during the campaign season.