Spinning reels work fine. It's just a preference thing. Especially when dealing with hatchery brats.
Also, with braided line, you can fish heavier line, but still keep a small diameter.

When the water gets low and clear, as if often does during a cold dry spell in the winter/late spring, it's nice to be able to toss size 1 to 3 spinners as well - or tiny egg clusters...

When fishing for nookies, and you really need heavier line, then I'd agree that you're better off putting the spinning reel down (but I still find myself using mine now and then and doing fine).