I would think a laser powerful enough, with enough wattage to cause near instantanoeus ignition would be too large and require too much power to be practical. It would also add a large monetary cost. You can aim your laser pointer at a primer for a week and it won't get hot enough to detonate. Also, ignition with a small enough laser to incorporate into an action would still be much slower than the milliseconds speed of conventional spring actuated firing pins. Some things are very tough to improve upon in a practical and cost effective manner.
