I don't know the answer about whether or not they have something against Jovi. You are right that they do sometimes feature the older bands on the cover. The last issue I received was in early August of this year.
I wonder what their subscriber demographic is these days. You know, the band members have often said they are not the critics' favorite. Maybe others will have more insight than I do.
There are other older bands that have (in my opinion) warranted more coverage, but I might be biased toward those I keep up with and like best. I was wondering similar things about Rolling Stone magazine for not mentioning Peter Frampton's first studio album in I think it was 9 years when he released "Now" in 2000. Then, he released an instrumental rock album/cd and it went largely unnoticed other than his grammy that did not get aired on the awards show
So maybe they do just have some they like better than others.
I am reminded of the lack of Jovi nomination for the RnR Hall of Fame. This topic reminds me of that topic, if that makes any sense.