For what it’s worth, others (including me) have posed this and related questions here and at WUS before. A recent example:
https://omegaforums.net/threads/concealed-clasp-bracelet-for-smp300c.140252/
My 300m professional bracelet is back in for warranty service with Omega for a second time—the clasps on these divers are very poorly made. —Or at least the one that came with my watch originally was, as was the first replacement I got. Could just be bad luck, and the third time will be a charm. (I’ve been told that it’s a known issue with a known solution; just haven’t seen the evidence myself yet.) In the meantime, Omega was kind enough to send me the blue rubber strap on the house, which is not a cheap item (for the customer, anyway). I appreciate that, though I don’t think I’m a rubber strap guy in the long run. I will say, it appears to be a very well made and extremely comfortable option.
That said, the consensus seems to be that there aren’t any really great alternatives that will fit properly. (The aforementioned aftermarket bracelets are probably ok, but I’m not exactly sure what benefits they offer.) The OEM bracelet looks good, imo, and the lack of taper doesn’t bug me as much. It’s a massive, chunky watch, and that’s part of the look. For me, it’s the huge clasp on the underside of the wrist that I find uncomfortable (and malfunctional too, of course—a separate issue). I wouldn’t say it’s wrong for the watch: it’s a diving clasp with a very well conceived microadjust mechanism. It’s just wrong for me, and I didn’t come to that realization until after the return window had passed. Mea culpa. But I do the love the dial, and the watch performs superbly. If they made a desk-diver bracelet that fit it properly, I’d probably call it perfection.