Though many see her, as people tend to see all Daedra, as an evil figure, I see something different.
Namira is patron to "repulsive creatures which inspire mortals with an instinctive revulsion". But tell me, does the fact that something makes you feel disgust mean that it is inherently bad? For example, my assorted neurodivergences often inhibit my ability to bathe on a regular basis. I've managed to get it down to around once a week, but I recall that at one point it had been literal years since I had taken a shower. This is, objectively, pretty gross. But it is not evil!
Now, consider the beggar, a class to which she is established as being patron. There are many in our society who hate that they exist, not in the sense that "it sure sucks that people get put in a position where they need to do that" as is entirely reasonable, but rather in the sense that they would rather install spikes on their windowsills to eliminate the possibility of their building sheltering a homeless person than do literally anything of use. I hope you agree, dear reader, that these people's disgust does not take precedence over the right for every being to live a happy, healthy life. Even vermin has a right to exist.
And, speaking of vermin, let us return to the decay mentioned in her title. While it is understandable that we collectively have this revulsion instinct, as many of the organisms involved in the process of rot can have deleterious effects on the human body, it is also undeniable that it is an important component of life on this planet. After all, what is rot but the process of recycling the dead so that life may flourish? In this way, perhaps Namira could even be considered an earth goddess? I've just googled that phrase, and found the term "chthonic", a Greek word that when applied to deities carries the dual associations of "soil" (and by extension "agriculture") and "the underworld" (and by extension "death"), and while this page is saying that no god "is" cthonic, it's more about the difference in ritual when you're calling on different aspects of a figure, it certainly shows that I'm not the first to make this connection. (It's also interesting given that one of her other spheres is "spirits", but I don't have much to say on that.)
Back to the point: We fear the dark because we know not what lies within it, but in truth it shrouds predator and prey equally. It just so happens that another of Namira's titles is "The Great Darkness"! To be unknown is a blessing to many, from those for whom having their true self revealed to others would put them at risk of persecution, to those whose problems are as simple as "having too many people trying to interact with me makes me anxious", to those such as myself who simply enjoy the concept of mystery (if you are familiar with Homestuck, it may or may not come as a surprise that I am a Void player :) ).
While many would rather not percieve or acknowledge the things in Namira's domain, this very fact means that her aid tends to go to those who are most in need of it.