Lately, the Alliance has received WAAAY more character focus than the Horde.
In Legion, the Horde had nothing after the Broken Shore. Absolutely nil, you could see all of the Horde plot points on an Alliance toon with the exception of Vol’jin’s funeral.
Meanwhile Anduin took over as High King and had his few moments. Velen, we followed all expansion as the Draenei story was entirely explained and fulfilled. Turalyon and Alleria stepped back in and had a patch to get introduced to players. Khadgar (while technically neutral still has strong ties to the Alliance) was the cohesion between all of the different orders and factions working against the Legion. Illidan almost exclusively hung out with Velen and Khadgar. Malfurion and Tyrande had a zone / dungeon / raid dedicated to their romance and backstory. And Genn has been featured in every expansion since he came into the game as an advisor / uncle figure to Anduin. He has had huge character development on and off screen. Not to mention Varian having the most epic and heroic death possible at the beginning of the expac.
Our new warchief showed up for a single cut scene in Legion and then disappeared for the rest of the expansion. It has been an expansion and a half and we still have no info on her infamous deal with Helya. Vol’jin was killed off to set up this god-awful BfA story line. Thrall’s character was butchered several expansions ago and hasn’t had any character redemption since, which was really damaging because his story during WC3 was THE defining factor for the Horde in Original WoW. Noble savagry, not giving in to evil and bloodlust, everything Sylvanas isn’t. He did temporarily pull it together to kill Garrosh (which threw him right back into a guilt spiral.)
Forward to BfA and Jaina is stepping up as the focal character. She is a leveling story NPC, war campaign NPC, raid boss, faction leader, and she will be working with Horde players come 8.2 to rescue Sir Bloodhoof the Useless. (Not the first time we have had to save him, either.)
Sylvanas has done almost nothing since War of Thorns, except make some snide comments, threaten me, and show up in a few role play scenes in between events.
So really the Alliance is almost out of characters to develop, everyone else has had their moment. The only open story line right now is Tyrande being pissed off and sick of inaction by Anduin, and what Anduin is going to eventually do about it.
tl;dr - I would like to see some Horde development I can be happy about, instead of the outcomes being “dead” or “Bloodthirsty psycho.” I want the noble savagery of the Horde back, good guys with a bad past, the beat-up underdogs trying to hold off the world so they can survive and rebuild. That is what drew me in. If I want to be a genocidal bad guy I will load up my special necromancer Skyrim save and murder all of the townsfolk.