Well, I'm about to find out what I do and do not like a baitcaster for. I bought 4 new casting setups this winter with the idea that I would make a good-faith effort to find out what the big deal is.
Until this year I used spinning for everything. It never occurred to me I would ever want or need to get a caster until recently. Crankbaits, spinnerbaits, jigs, texas rigs, even frogs, I am able to fish effectively, intuitively on spinning gear. I grew up fishing for other species (catfish, panfish, pike, walleye) with spinning tackle, it's what I learned, what I've always used, with no problems. It's what everybody I knew had always used, for everything. Still very few of the people I ever see fishing for anything around here, including bass, use casters (occasionally, but rarely). Granted, I don't do tournaments, so my taste in gear has virtually no influence from tournament folks. I've also never followed the pros that closely (a little bit) until recently, so it never registered that I should use casters because they do.
So when I hear people discuss whether spinning is "necessary," it sounds like a communication from an alternate universe: In my experience, it is baitcasters that are of questionable necessity! Spinning has its problems -- working moving bait with heavier spinning gear can be awkward unless you're just doing a straight retrieve. Line twist is always an annoyance unless you're using braid. But there are no backlashes, and I have zero problems with accuracy... I often hear that that casters are "more accurate" -- again with the alternate universe: spinning rods lack accuracy? I cannot comprehend this; surely, this assertion is just an effect of experience.
In any case, we'll see how it goes with the new casters. So far, pitching to targets in the backyard is almost as easy as it is with my spinning rods...