Rods & Reels...
There are many techniques and lures that are best used with a baitcasting combo. Here are a few reasons why you may want to use a baitcaster...
Being able to use a heavier line – With a baitcasting reel, the line comes off directly through the line guide and straight through the rod guides. This makes it easier to use heavier lines, from 10-20lb test, and heavier lures. A standard baitcasting setup can easily cast lures from 1/4 to 1oz, and more.
Casting with less line twist – Spinning reels are notorious for line twist, and line twist is the enemy of good casting. Baitcasters spool the line at a 90º angle to the spool axis, and this means the only line twist passed on into your line will be coming from your lure, this happens a lot when fishing soft plastics.
Full Send Casts – Baitcasters easily outcast spinning gear. The line comes off the spool straight out of the rod guides, compared to the uncoiling of a spinning outfit. For bombing my hard baits, you can’t beat the baitcaster.
More Power – Baitcasters are capable of more power than spinning reels, thanks to their spool layout and design. The spool is in-line with the handle and gears, so the reel can apply more power and torque. Also, because the handles are mounted directly onto the reel frame there is no lever arm to cause flex when reeling hard on a fish.
More Control – Baitcasting reel combos provide a high degree of casting control compared to spinning gear because you can control the distance and speed of your lure by thumbing the spool during the cast. Once you become proficient in their use, you can achieve pinpoint accuracy with your casts, allowing you to place your lure exactly where the fish are.
I believe the key benefit of the spinning rod is that you can cast very light lures with it, and that difference is because of how the reel works. The line can flow off the spool with no resistance. It spills off freely in big loops, and spinning rods have a larger first guide to reduce drag as those loops come off the reel.
I love to use topwater baits so I favor a spinning rod because it's ideal for presenting my custom poppers. Not only can you cast light poppers and spinner baits, spinning rods also lets you throw light soft plastic for finesse fishing.
While spinning rods may not give you all the power that a baitcasting rod can when it's time to muscle a big fish out of heavy cover, it's good at what it does, which is enabling extremely long casts and letting anglers fish with lighter baits like poppers and soft plastics.