I used Amplitube for a long time, mainly because of their movable mic and swappable speaker cabinet section. The Mikko plugin is a completely wonderful alternative, and far better for a Fractal user because of it's instant IR export function, among many other reasons. The amps in Amplitube were not right at all, and I hated it for that reason, in addition to the worst customer service, virtually no updates, and a lack of dynamic feel. Here's an example of the trade off between usability and looks: just try either of their officially endorsed Recitifers in Amplitube. They are so lacking in gain, it's unreal. I can't imagine how Boogie decided to license to them. I think their UI is really really nice looking, but their sound is lacking in direct proportion to the looks. I think they doth protest too much. It's like their trying to say, "Look how great you'll sound; see how good we look?" Not to mention the utter inability to approximate real world gain staging in Amplitube; the aspect of real world gain staging is another thing that makes the AxeFX the best thing on the planet. I'd much rather have everything that Fractal provides.
I'm a pretty new Axe FX owner, but for the few amp models I'm pretty familiar with in the real world, it's dead on to my experience, and that's worth everything to me. I think skeuomorphism can be a problem in that it can be a distraction from what's important. In the case of IK, I think they just poured all of their resources into looks, spent time hounding rock stars and engineers for endorsements, and left the sound to rot by not updating any models (instead selling new versions of old ones, at a snail's pace). The point of the AxeFX for me is very much to forget about the AxeFX, and my guitar, and just focus on the music itself. The AxeFX is so good that I don't need to worry about it constantly, tweak it all night long, and realize at the end of the night I've not spent any real time practicing or playing. I could spend forever working with it, but only out of joy and experimentation, because of it's world of features, which is awesome, but for me, it's a trusty tube amp, reliable and ready to go at 3 a.m. with no compromise in sound or feel. With Amplitube I really did fall into a bad cycle of constantly trying to find something that felt right without significant problems, and it was just demoralizing. It took a long time before I could even consider owning an AxeFX, but it really changed things for me, and, having spent so much of my time using pretty programs that sound lifeless, I'd jump on a command line modeler if it sounded better. To that point, I don't think the AxeFX UI looks bad; it's exactly what you need, right in front of your face, getting you to all the important aspects of your tone right away. I think it's some of the same thought process behind Cliff telling his fellow engineer not to label the FAS IRs with specific mic placement details: he just wanted it to be based on using your ears. That's the basis for all good audio engineering, and, by extension, guitar tone; just move knobs and sliders until it doesn't suck. Then, if you really value the sound itself as an art, you can craft it ad infinitum like the best engineers to create something sublime.
And that gets into the question of, if you only need your ears, why does the accuracy of models matter? Well, it only depends on how much you trust the designs amp designers, and how much you think their work is a link to good tone. I'm not an engineer, but I totally trust that all of the great designers, and the modders, are at the very least a good starting point. Obviously Cliff is one of those designers himself, not only with his only FAS models, but with the very specific suggestions he provides to correct for the inherent drawbacks of others' designs. I'm in no position to judge either way, but I trust Rupert Neve too, based on how much of all good sound we know comes directly or indirectly from his ideas about how it should be. I don't at all think about IK that way, quite the opposite.
All this is a very long-winded way for me to say, substance over style, every time.
