There are actually quite a few things you can do in mechanics with no calculus at all: statics (hydrostatics too), uniform motion, Newton's laws, the basics of energy, momentum etc., so no, I would not say mechanics without calculus is useless. And if you know calculus but not the proofs of calculus, then it is not much better than not knowing calculus, isn't it? The only thing that matters is the idea of "limiting" or approximating something in many small steps, and then saying that in the limit everything works out. Archimedes knew this long before calculus was invented. This is the idea behind many calculus proofs anyway, and exactly why calculus is so important to physics. In fact, if you know calculus but not its proofs, then it seems it is sometimes used as a magic tool where results pop out, with not much intuition for WHY things should be so, and it is usually the idea of limiting that is obscured. Calculus allows you to do a lot more, but it doesn't necesarily add insight.
I know I'm blabbing and not saying anything precise, sorry...