wah wah wah Bioware doesn't ascribe to "Elven Exceptionalism" wah wah wah.
Sorry your favourite race turned out to be just a culpable for the ills of the world as every other group in Thedas. Bioware's even handedness in making NO innocence is obvious derived from hatred of an imaginary species.
Seriously? I really HATE elf fans just as much as I hate templar fans and mage fans. You people are fraking crazed. 'My preferred imaginary group are all white hates and innocent it is those other imaginary people that are evil. Bioware sucks because it is obvious hate that motivated them to write in content that proves my preferred group isn't 100% perfect.' Just STFU
Gamers are the WORSE consumers in the world.
No, allow me to try and clarify in response to your pigeonholing.
I am not speaking for more extreme or rabid fans either. However, it is clear that there are aspects of how Inquisition treats elves and the dalish that comes off as unnatural compared to previous games. It essentially comes off as heavy-handed "back-tracking" rather than being even-handed expansion.
Just as one example: The Dalish 3 mage rule is a lazy retcon. It serves as a retcon for the fact that it contradicts with the essence of dalish culture and how they have overall treated their mages with a great deal of respect, trust, honor and humanity. It also makes no sense to throw out extra mages to die when the dalish hold mages as valuable since they believe that all elves had magic once. This is also something that was NEVER brought up in previous games or even previous books for that matter.
It's clear that this rule was thrown in just to put the Dalish down a peg so that they don't seem vastly better in terms of mage treatment than the Chantry. But it's too little and too late after two games of showing how and the Circle system was bound to fail with a civil war as its result. For instance, The Chantry also authorized hunting mages outside of the Circle and assume that they're all dangerous regardless of whether they practice demonology/blood magic or not. Regardless of whether they use their magic for good or evil. As opposed to the Dalish who are willing to take-in outsider elves from the Circle and the Alienages with open arms and some clans are capable of having reasonably amiable relations with human settlements.
So even if this rule isn't a retcon (it is, but still), it would still fail in its apparent attempt to put the Dalish on the same level as the Chantry. Because the Dalish would STILL be far better in its treatment of mages than the Chantry.
Abelas' account doesn't absolve Tevinter of destroying Arlathan or enslaving its people for hundreds of years while destroying their culture and dignity, but the game acts like its all the fault of the elves.
The Red Crossing incident doesn't absolve Orlais of their part in the escalation of hostilities and stripping the elves of their autonomy and kingdom, but you wouldn't know that from how the game treats the situation.
Oh and note how the game is quiet about the Alienages and the crap that they have to go through? Probably because that would blow a hole in the writer's attempts to say that "elves aren't better than humans" narrative that they're apparently championing. No wonder we couldn't have a City elf Inquisitor, they'd likely let Orlais burn considering how notoriously bad that the country treats the elves there.
Overall, my point is that there's a way to portray the new information that the game brought up and Inquisition went about it in the wrong way. Hence, it comes off as annoying heavy-handed brow-beating rather than naturally introducing a new dynamic to the elves of Thedas. No one was ever saying that the elves of Dragon Age were perfect, yet the writers are going out their way to bash an already downtrodden target for sake of an agenda.
That's what "elven fans" are against. Bioware is better than that.
_______
As for the OP at hand. I'd say that the reason that Morrigan seems more competent is because she had a great start while Merrill had to work from scratch. Morrigan is clearly the stronger mage, but that doesn't mean that Merrill's worthless by comparison.
Morrigan had an edge in that he was taught by her mother who was possessed by Mythal herself. She also had access to wider forms of magic which allowed her to build on her knowledge step by step.
In that context, I'd argue that Merrill did a great job with what she was working with. She just didn't account for Marethari's actions. Merrill knew what she was getting into and made precautions to protect herself, among them was also teaming up with Hawke and company. It's a testament in itself that despite using blood magic and dabbling in demon arts, Merrill never allowed those things to control her. She used them as tools for a greater goal, she recognized those tools as being dangerous and yet, she never let those tools control her in the end.
And as Inquisition shows, Merrill's efforts do pay off. Her eluvian is shown in the Crossroads if it's not destroyed in DA2.
That's amazing. Merrill created a working eluvian from scratch. She found a shard of an ancient magic mirror, restructured it into a full mirror and got it to work WITHOUT the demon's help.
"claps"
For all of her knowledge and power, my lady Morrigan has yet to top that.