I agree that leveling is way too fast. I have so many friends that potentially would have started playing wow regularily hadn't it been for the bad leveling experience.
That is entirely your subjective opinion on the matter of levelling. Also yeah they weren't mandatory since there were other progression paths open. Crafted gear from Mogushan patterns, BoEs and Heroic Dungeon gear were more than enough to enter Mogushan. I don't think you understand what mandatory means.
If leveling is too fast, blizzard has to add more garbage at level cap because it is too easily content-drought.
Not really. There is content for every type of player. Feel free not to do it. The point is just because you don't like the content does not suddenly stop it from existing or that everyone shares your opinion. I despise PvP in WoW for example. Does that mean it stops being content in the game? Not at all.
For example, I hate making gold in game. Is that an excuse for blizzard sells wow token. If blizzard pisses you off, the game economy will collapse because the game becomes P2W.
I got arena title S1 legion without even having unlocked my third relic slot. Shit, I still haven't cuz I just forget to do the dungeons and have only done LFR on that toon like.... almost 2 cycles?
I wasn't happy with the launch and how alt unfriendly it was, but now having no need to grind rep (unless for professions) or AK... it's not pretty super alt friendly, too alt friendly. Balance has never been a word in Blizzards vocabulary.