There's years upon years of official artwork featuring Alexstrasza without pants. I'm not against Alexstrasza wearing pants but it seems like an odd design choice. Alexstrasza's model in WotLK was a modified version of Sylvanas' model but for some reason they decided to make her skip pants and wear a translucent cloak. I'm assuming that was an intentional design choice rather than miscommunication or a bug when copypasting Sylvanas' model.
I'm also assuming Blizzard made Alexstrasza look like Sylvanas in WotLK because of resource / time constraints. Now they have the opportunity to redesign her and give her some unique armor. It's not like anyone will care anyways since the last time she played a major part in WoW was years ago and I doubt anyone really remembers / cares what her model looks like. Why then instead of giving her a completely new look they decide to just give her pants? They obviously had a redesign in mind when they gave her pants otherwise they wouldn't have bothered. If they wanted to redesign her, why did they make her armor look more similar to Sylvanas' armor instead of making it more distinct? Is it a fashion statement in Azeroth?