Euphoria is right. Cheek concavity, as he calls it, or at least flatness, I would say, is essential for any man who aspires to look good. And by this I don't even mean S curves, prominent cheekbones or anything in that sense. I just mean flatness or even hollowness (concavity) in that area defined by the two points up from your zygomatic/orbital complex down to your paranasal area. And for that you need good cheekbones/orbital complex, good maxilla and little to no fat. I dare you find any man who looks good and who does not have that concavity or at least flatness. Good looking men - they may not have an S curve, but they will be at least flat between those two points. And the opposite is always true. The opposite cases are almost always accompanied by excess soft tissue - fat, skin, even muscle... (so you have under-eye hollows and nalsolabial folds typical of ageing or of faces in fat people), malar-orbital and paranasal deficiencies. Solutions - augmenting the zygomatic/orbital and paranasal areas or taking away any fat in between. Some doctors venture to do micro-liposuction there, although apparently it's risky as it can lead to skin ptosis. But I know some of them that do it. It can work on some younger patients with good skin elasticity and you may find yourself with good prominent cheekbones even though you did not have any implants or osteotomies in the malar area. You simply removed the fat, a process that chiseled your face. Even a little can make a difference, where indicated (not always). You may even get the S curve. Do not confuse this with buccal fat - it's a completely different fat compartment in the face. That's why buccal fat removal doesn't work. People expect to have a model, chiseled face after buccal fat removal and yet it does s**t except in some rare cases where it is a problem to begin with (very rare in non-fat men).
Don't neglect the paranasal area as it is crucial for right support there. You need flatness/concavity in anything in-between these two areas, and you need good bone support/projection in both these points, if you're going to have flatness/concavity. Weak/deficient paranasal area is almost as problematic as weak/deficient malar/orbital area. Why? Because your soft tissue - especially true as it is ageing and descending - does not have enough support. And do not think of your late 50s here, think of a process that starts in your late 20s. This creates the complete opposite of cheek concavity look. My point is, you can have great prominent cheekbones, but if your paranasal area is deficient, you won't have cheek concavity. For a concave curve, you need two good points mathematically, one is not enough.
To sum it up - if you're flat there, you're probably fine - you don't have to do anything at all and stop obsessing as you're probably looking in the wrong direction. If you're concave, you may even have the S curve. But if you're not and you want to look good, you'd better start augmenting or taking away from the right places. Or accept that you'll never look good. Again, I dare you find any example who would prove that I'm wrong. Whenever I see an ugly male face, it's always either a very weak jaw, a very long mid-face (philtrum especially) or the opposite of cheek concavity. Most often the last one.