I think their benefit is overstated. They help, they are harmless, but they burrow only deep enough to barely cover themselves, and in compacted sand, I do not think they would do much if anything to help.adding MTS to keep it turned over.
My experience with sand... compact, compact, compact... Within only a few months it got so hard I could not poke my finger through it. Plant growth slowed down, I had dead spots all over the substrate where the compacted sand cut off oxygen and tuned the sand black from rotting organics. It smelled like rotting eggs, and some of my fish started getting sick.. lathargic, stopped eating. It was a huge mess.
That was several years ago. Since then I have tried growing plants in sand with no fish, because sand was cheap. My Cryptocorynes will simply not grow in it. Plants that responded well from water column ferts and plenty of light seemed to do OK.