First, the Time Machine. I think it's considered important because this is where science fiction began to have IMPORTANT MESSAGES about society.
I hate science fiction that has IMPORTANT MESSAGES. I do, nevertheless, thank H.G. Wells for writing this, without which we may not have had The Terminator series of movies nor Bill and Ted's Excellent Adventure.
Now on to The Invisible Man. Who authorized a book about an invisible man that doesn't even have one scene in a women's locker room? And it's not because it's all serious, either - Wells has lots of slapstick scenes with tripping and injuries that are supposed to be funny (but aren't).
Also, it never occurred to anybody to keep plenty of flour about, for throwing when the invisible man was around?
Yes, I'm responding on the wrong level - with pragmatic complaints about a philosophical thesis. But, really, I'm comfortable placing these with Frankenstein and Dracula - works that are more important for the cultural touchstones they left behind than for reading in their own right.