There are several factors that play into nomination, including recent activity and of course quality of contributions, but also just "forgotten" artists that have never (or not in a long time) been spotlit. I try to balance these factors out, but of course it's not always perfect.
On the other hand, I try to not spotlight artists that have already been nominated in the past few years, which for example means that some of the artists on your list would also not apply. In general, new suggestions for the spotlight are always welcome, so I will add a few of your list to the current spotlight.