I somewhat agree with this.
X-Men PFs, specifically the 90s/Claremont/Jim Lee line up, have been years in the making. We're awaiting Jean, and still no word whatsoever on the characters missing from that particular roster: Beast, Iceman, Prof. X, Storm in White, Jubilee, Bishop and Archangel. That's still half the team. And PFs are on their way to double the cost of what Wolverine and Gambit cost. Getting the last members of the roster could be tough!
Meanwhile DC, a newer license being produced after the start of this X-Men line up, is pumping out characters and seems pretty dedicated to the JLA (although we don't know when the next JLA piece will be either, we've seen working designs for Flash and Aquaman). Yeah, it's the JLA, top level and most powerful for DC, but really, in terms of mainstream popularity most of the JLA outside of the Big 3 don't have the popularity of much of the core X-Men members.
The ball needs to get rolling on finishing off the 90s line up, and as much as I like the Storm PF, I'd rather SS get the rest of the 90s roster before doing anymore 70s or modern costumes. The X-Men PFs could be the most cohesive line up SS has done in terms of all the characters in costumes they wore during the same era to make a complete team. This is how the LoTR PF collectors feel about SS not completing the Fellowship in PF... in these cases SS needs to finish what they start!