I think what Mumei is saying is Sarkeesian's work could be better received if it were clear that her enterprise is (somewhat disinterested) analysis of video games rather than an outright attack on the medium.
I think you (and Mumei) may be right.
Framing the analysis as an attack on lazy game design in general could also work.
Many of the points being made point to weird habits the industry has gotten into, and show how modern games are simply recycling tired methods of eliciting a reaction. Many of these are perfectly good arguments in their own right, and even when we see them fully in context (playing the game, immersed in the world), they can often come across as ham-fisted and ultimately unnecessary.
I think the important thing for people to remember is that all Sarkeesian is doing is pointing out the ones that primarily paint female characters in a negative light (less agency, more vulnerable, only sexualised, etc. etc.).
That's her thing. That's what she set out to do, and now she's doing it.
Sometimes she misses the mark, picks a bad example, or gets too carried away with her "agenda". (Call it that if you want, because that's ultimatley what it is.) But this doesn't make the issues she's pointing out less real. I've come to learn this during the course of watching her videos, and while I really dislike the kneejerk Twitter posts and articles flooding in to jump on the bandwagon of "sex in games is bad", I've started to become sick of the ignorant side as well.
Just try and be aware of the potential problems at hand. That's all people are asking for now.
A lot of people counter with "you could say the same for [such and such] in games".
Of course you could. No one is stopping you, so if it's that easy, go ahead and try it.
People have probably tried before, and there was no doubt a murmur of discussion before it got put to rest because it simply wasn't that big of a deal (at the time). Portrayal of females and equal representation in games is a big deal right now, because more people are noticing how we've accepted a twisted standard. I don't know what this standard is a result of (and I don't really want to trudge through a mess of human societal/psychological history to find out), but I do know that I want to see games attempt to do better.
I've played and loved games where I've strolled through prostitute-filled streets, beat up guys (and gals) who beat up gals (and guys), gone to a strip club/gay bar, and all manner of other things I wouldn't (even necessarily want to) do in real life.
The main question is twofold:
1. Whether you're happy with how these things are portrayed.
2. Whether they're indispensable to your enjoyment of the game proper.
If the answer to either one of those is "not really", then consider that there might be a problem.