Is it better to wait a couple of years after having a dental implant done to put in a dental abutment?

No- you should wait the amount of time that your specialist advises--typically from 3 to 6 months depending upon the location in your mouth.The last research I viewed indicated that leaving the implant without the final crown is NOT as healthy as having the final post (the abutment) and then the final crown on it.

I don't think there is any advantage to waiting. You only need to wait until the implant is integrated, meaning the bone has attached to the implant and it's ready to restore. If you don't have the abutment and crown placed then the implant body will stay buried in the bone. The surrounding teeth can continue to move while you wait however, and that could complicate things whenever you do decide to place the abutment and crown.