And if we want to understand Tolkien, that's great. But, if I want to critique The Lord of the Rings, for example, Tolkien simply doesn't matter. We can examine LotR in the context of the time it was written, but, largely, any interpretation of LotR has to be based in the text itself.
Anecdotes from the writer's life might be interesting, and, they might spark a talking point, but, unless we're actually discussing the author and not the works, the author's life is largely irrelevant to understanding and interpreting a work. Sorry, J. K. Rowling, no you don't get to after the fact declare Dumbledore to be a gay character when there is absolutely nothing in the text to even suggest his sexuality in any direction.
-----
On the topic of the vitriol regarding Lovelcraft.
One has to remember that Lovecraft was, until very, very recently, given a very prominent place among the authors of the genre. The 5e PHB, published not that long ago, places Lovecraft in the list of inspirational authors alongside Tolkien and other great genre authors. Heck, the term, "Lovecraftian" is used to describe works, completely expunged of any racist meanings. Think about that for a second. You're a writer who Lovecraft would have thought should have been castrated or killed, and your works are being called "Lovecraftian". Additionally, you're a really, really great writer and you win the highest award for Horror out there - the World Fantasy Award - and you are given the bust of a dude that would have thought Hitler didn't go far enough.
And, until very recently, if you complained, you would get reactions like you see in this thread - oh, you have to understand... it was just a product of his time, we don't really think like that anymore... you should be thicker skinned about it... we have bigger issues to worry about... hey, you just won a major award for your work, you should be grateful...
So on and so forth.
So the vitriol we're seeing today isn't really any different than the vitriol you would have seen in any other year. Thing is, instead of being pushed aside, sidelined and ignored, people are actually listening and actually making changes - the bust of Lovecraft is no longer the World Fantasy Award. I will be pretty shocked if Lovecraft's name appears in the newly released 5e PHB under inspirational reading.
The vitriol is largely a reaction to the privileged position Lovecraft enjoyed for nearly a century, simply because he was white and only attacked minorities.