Are cycling shoes really necessary with cleats?

It depends on how you use the bike, but after 15 years of work I'll tell you that cleats are really only useful if you do serious bike touring or competitions - for normal use regular sneakers work just fine, even if it's not the same pedaling efficiency. I personally have always avoided them because I don't like the idea of being "glued" to the bike, but I'll admit I could be wrong about that.