How do you know Legion got a population increase. Blizzard stopped releasing subscription counts since a year ago. I may be wrong, but there isn't really any way to prove things one way or another. I don't really care much either as I don't really think retail populations are a good representation for private server populations. It's pretty obvious bugs play a role on private servers. A realm that has literally nothing working and you can one shot another player will likely have few players, naturally (I think we can definitely agree on this, right?). Furthermore realm design must play a role as well. It seems more players prefer high exp rate realms than blizzclones, for example. Clearly these both are among many factors that affect private server populations but not retail.
Because this is the only data we have to work with when it comes to studying what factors affect population on Warmane? Do you have any other data that can be used to better study population changes? If so, I would love to take a look at it as well.
Which tournaments did these "world-class" pvp players play in? If possible, can we also get some names so I can read up on these players' issues with S15?
You seem to be implying that I did not play the game pre-Cata. I've played the game since vanilla (before Naxx was launched mind you) and I also played on private servers since the very first ones on vanilla. I also played both the end of MoP and start of WoD on retail. I would appreciate if we can focus on what my arguments are and less on my experience. I do believe this is considered an ad hominem, no?
I don't think this is correct. As stated above I played MoP (at least 5.4.8, I didn't play the beginning of the expansion, that much is true), so I naturally don't fall in the second category. As for the first, does that mean anyone that enjoys playing MoP on a private server is looking through rose-tinted glasses. If so, can't the same be said for people still playing on WotLK after 7 years of it ending on retail?
Since it seems to be so difficult I will sum up my points so we can focus on what I am claiming and if there is any merit in it.
OP asked why WotLK has more players playing on it.
I showed population counts from 2 years ago and showed how the populations were equal when MoP was the main focus for the devs. The realms were in worse condition then, yet had more players (compared to today).
I then hypothesized, based on this, that population seems to be closely linked to development focus.
I didn't say one expansion was better than the other. I didn't say Warmane should focus on x,y,z. I only said populations seems to be closely linked to development focus. I honestly don't even think our debate matters, (I don't care if I'm right or wrong, I'm just doing this for fun) and I'm sure over time we will see more people on MoP because either I'm right and fixes will bring more players, or I'm wrong and "nostalgia" will. Heck maybe population will never increase to 8k again (I'm pretty doubtful of this happening) and I'll just eat my words and enjoy playing MoP wherever I can. But, as long as population increases, I'll be happy, regardless of the reasons for it.