An interesting idea, but it would be prohibitively expensive; in terms of Delta-V and cost.

You are already launching a satellite into an orbit where it will try avoid existing space debris. So, anything added to the payload to de-orbit space debris would have to spend delta-v adjusting it's orbit to match that of the space junk. Then it would need enough fuel left over to de-orbit the target.

I think it would be better if a certain amount of the launch cost would go towards a fund meant to de-orbit space junk.