The vast majority of the XMA competitors DO have a strong traditional base (though I am sure there are some glaring exceptions). The Extreme (XMA) division is but one division on the national open circuit. In other words, they have given these guys their own place in the sport to do what they do. If anyone wants to do traditional or creative/open forms, there are still the divisions for those as well. Creative/open allows a competitor to create their own form and highlight their athletic abilities, but is limited to martial arts techniques and excludes gymnastics. There are no inverted (upside down) maneuvers nor any rotations greater than 360 degrees. Traditional forms of course is going by the traditional forms of the practitioners style.
I see nothing wrong with XMA for the advanced kids and teens as a bonus after they're regular curiculum has been worked hard and is solid. Basically dessert after a well balanced meal. In my school, we have a XPT (extreme performance training: our version of XMA) class that they learn competition weapons (tournament-style kama, nunchaku, bo and broadsword on a three month rotation. Our normal curriculum consists of the FMA's for weapons training.) and these aeriel "tricks".
This is our version of "black belt club" and they pay an extra fee for it. However, they are required to be VERY solid on their basics and curriculum and be an A-B honor roll student to be eligible for this. In other words, they have to be solid on the things that count to have "dessert". It helps motivate them and builds their athletic abilities to higher levels which DO carry over to their regular training. In the same classes, we also give the same students additional work on their grappling, boxing, kickboxing, ect. This is just basically a bonus for the students that you have to chase away at night with a stick to close the doors.
At least 3-4 nights a week, I have a group of teens and young adults that stay after classes and are working on this stuff until (and somtimes after) I am ready to close up and go home. These are usually the same ones though that are the best kickboxers and grapplers in their age groups. They will often switch out in groups alternating between "tricking" and rolling (submission grappling) after class. Also many will work basic drills during down time (resting) from their tricks. Personally, I would prefer to have them spend more time on the curriculum drills, but if this motivates them to excel and they are still keeping up their school grades, then I am all for it. Without it, I really doubt that I would be having such a large group putting in all the extra effort.