Yes, I do happen to think that the death of Bobby Sands did indeed increase violence in Ireland during the 1980s. The situation there was already tense, and the fact that the United Kingdom allowed him to starve to death in prison showed they were ruthless, and that more force against them was needed.
Bobby Sand's death while on hunger strike was just what the IRA needed to rally support. It is unfortunate that someone with such passion about his cause would die in such a way. Such people deserve to die of old age, or at least in some kind of conflict. When you hear that such a rebel died during a peaceful protest, it inspires you to learn more about his cause, and it becomes easier to understand. Because of this, the IRA recruitment increased, and with more troops on the ground, you inevitably have more casualties.
Bobby Sands was a martyr for the IRA when he died in prison on a hunger strike. The Irish Republican Army continued to bomb Protestant targets for the next 10 years until a peace accord was finally ratified. Sands's defiance kept anti-British sentiment alive for years. Even now, there are tensions in Belfast and in Northern Ireland even after the peace accords from 20 years ago.
I believe Bobby Sands' death due to a hunger strike while in prison was directly responsible for much of the violence in Ireland in the 1980's. The IRA had dramatically increased membership immediately after the death of Bobby Sands. There was much anger and resentment attached to his death and the hunger strike which preceded it. These circumstances contributed to more unrest in an already divided country.
I think that the death of Bobby Sands decreased the violence in Ireland during the 1980s, because Bobby Sands was no longer there to keep the issue current. Bobby Sands was the leader in the movement, and his departure made it harder for the violence to continue at the force at which it was.