First of all people dont want old content feeling relevant any more. Nobody liked idea of time-walking (even though some -me too- think its ok to do it from time to time) because most of us have played Wow many years and are bored with old content that we have already farmed so much in past. Wow is stuck in going to old stuff all the time. We had remake of Dead Mines and other dungeons. People werent too happy and most asked about why no new content is being made instead. Every time an armor tier look a bit alike older one people dislike it too.
I agree that xp is way too fast gained, especially during first 60 levels. I would prefer that these first 60 levels go slow (bit faster than during BC) so that people could both do quests in many zones and do LFG. Now you do 3 LFG and lvl up 5 levels so all quests become green. There are plenty of different leveling zones up to 60 but then its mostly one or other zone and at times just 1 zone to level. I would prefer if 60-90 were going very fast. They have least of diverse content.
People are unhappy that its more than year since last patch with new raid but they want pristine Vanilla with no new content ever. Contradiction. I bet if Blizzard fixed that Vanilla server people would whine that they want new, vanilla style content at scheduled times. Vanilla is not that much of content if you have leveled more than few alts in past and nostalgia can live a month or two. What then? If people cannot handle 1 year of no new stuff how will they handle Vanilla with no new things ever? Or do they expect Blizzard to give out content both for Vanilla and main game?
I think that Blizzard is in uneasy position having 100 levels, plenty of zones and making it still feel both challenging and not too slow. Imagine having to level 6 months to level up to 100. Would people do it? Imagine having to grind to gain level as quests wouldnt be enough to level up. I wouldnt do it.