Well, there's nothing wrong with a tanto in any transcendental or ethical sense. I don't believe tantos were designed by satan or anything ... well, at least I'm
pretty sure of that
Often, it's experience with a (Americanized) tanto that makes one dislike it. Yes, it's got some advantages -- like a thick point, for example. But it's got disadvantages too. The lack of a belly can be annoying for some jobs. The high point is difficult to control. The typically thick point is strong, which means that I might be able to pierce car doors, but it's more difficult to pierce the things I normally want to cut. You have to sharpen the thing in two separate stages.
Of course, many of these things aren't necesasrily inherent to the Americanized tanto. There's no reason you can't break format to clip or drop the point (the Benchmade pictured above does that a little), slap on a swedge and otherwise thin out the grind for better piercing, etc. But now you're still left with a belly-less, must-be-sharpened-in-stages knife that loses the tanto point strength benefits but still has other problems.
On the other hand, though they're are minority, there are folks for whom a tanto works great. They like the high-performance hollow grind on one edge and strong flat grind on the other, they don't mind sharpening in stages, they like an extra-strong tip for whatever reason, they don't need a belly for whataever it is they're cutting, they don't care if the tip control is imprecise.
Joe