Should they be less forgiving/harsher? I don't know, you alienate bad players if you make things unpassable for the average skill level- and honestly, I've played MMOs 15 years, I've played a dozen different ones seriously- the average player is unable or unwilling to learn, but they still have the right to play the game. If you up the challenge on everything though- well sure, that may make more hardcore players happy, but it's not like there aren't highly difficult content outside of basic dungeons/main story.
People also often equate having to group/spend time to find a group to challenge- like if you can do something solo, it's casual content but if you need 40 people it's hardcore and only hardcores should get it. This is something I've disagreed with since Vanilla WoW, and despite it taking months of 20 hour raid weeks to get through Vanilla raids, the content was actually very easy- it just required a lot of people spending a lot of time.
I do think, of course, that they should continue to include interesting mechanics in all content, it's one of the top things that is making me consider staying here rather than going back when Azshara drops, because I know in WoW that once I beat H-Azshara, everything else I can do for the next half year involves zero mechanics. Maybe that's just cuz I'm new, and admittedly haven't done any significant content yet- the hardest I've done is Extreme Ramuh. But just in ARR I've seen better 'easy' content mechanics than in 15 years of WoW outside raids, and just the ability to be interested in something other than raiding (and Legion's mage tower... gods that was fun) in a game makes the statement 'going the same route as WoW' in the title make no sense to me.
Like, think about your pre-level 30 rotation, before you get all the ninja or black mage skills added... that's still a more complex rotation than half the WoW classes. No really- I'm looking at the optimal summoner rotation guide and it's two minutes long. My BM hunter rotation is... use abilities with small CDs when they're off CD, try to sync your two big cooldowns, spam cobra shot if you have extra focus.
Just imagine that- being able to be optimal at your class with 3-5 abilities+ 1-3 CDs, where the rotation is 'use everything with a CD, then use the thing without a CD' because that is the pro guide for 90% of WoW dps specs in a nutshell. Ninjutsu alone is more complicated than entire specs in WoW, so no, no I don't think this game's at any risk of dropping to WoW's level.