You are right that this is an issue that will grow more prevalent as more people become aware. One way this can be addressed would be to dynamically adjust the minimum item level required to queue for Alliance Roulette based on the level of the job that is used to join. As an example, if you want to participate in roulette as a level 50 job, then you must meet a minimum item level of 70. If you want to participate in roulette as a level 60 job, then you must meet a minimum item level of 205. So on and so forth. Through luck of the draw, you may still find yourself in a lower level raid, but it would no longer be possible to force it.