I was all-spinning until about 10 years ago because...that's what I learned on, that's what everyone I knew always used, and it never occurred to me that I "needed" a baitcaster for anything....including spinnerbaits, jigs, frogs, etc. I did indeed use a spinning rod for those things and believe it or not actually caught fish. Nowadays I use a baitcaster and spinning rod each about 1/2 the time, and wouldn't want to be without either of them.
When I started using baitcasters, I discovered why they are preferable over spinning for many presentations. They are much better for heavy cover and most horizontal crank-and-wind retrieves, for instance. The learning curve wasn't as steep as I thought it would be -- I picked up on how not to backlash pretty quickly after a little practice (the braking systems on reels these days are very forgiving).
I'll still use spinning over casting for light lures, especially vertical presentations. I also still prefer spinning in current, as well as fishing from shore, where casting angles are limited by tree limbs and stuff. I do not experience the same frustrations others seem to have with spinning. For instance I find line twist mostly avoidable or at least managable as long as you are careful. Braid nearly eliminates the effect of twist, but even without braid, simply paying attention and occasionally letting out line to detwist a bit solves the problem.
Nor do I experience all the advantages people claim about casting, such as inherently better accuracy. I can easily match thumb control on casting gear with "finger-control" on spinning. I can pitch, roll-cast, and drop a bait with more-or-less silent entry using either.
My point is, it's not really possible to predict whether you'd find using spinning more useful or advantageous than a baitcaster. It depends on the kinds of water and cover you fish, the kinds of presentations and lures you use, your own preferences, comfort level, habits, and skill. You'll have to try it a bit to know.