There have been millions of fish caught with rods of all varieties, materials, powers, and actions. How many rods did your father have? Probably one. So, IMO, it is not a necessity to have a crankbait rod. But it can be advantageous. If you are using mono or FC now, lines with quite a bit of stretch, which equates to "forgiveness" when the fish hits, it may not make a big difference. But if you are using braid you will probably do better with a moderate action, which will be more forgiving, resulting in fewer missed fish due to too aggressive hook sets on the strike. All the crank rods do, regardless of material, is soften up the rod's reaction to the strike. In other words, consider it a system, line + rod. The system should be "harder/stiffer" for finesse applications, "softer" for cranks and surface. (treble hooks).
The casting characteristics will be somewhat different, but that's not compelling, and what works better for one caster may not work better for another.
As previously stated, if you're not missing a lot of strikes now, getting another rod won't be a big improvement. To me, bigger than the action difference is the convenience of having more setups, each for its own technique and lure, so lure changes won't be necessary so often.