This post touches so many topics, I will try to answer a few ..

"Why is it that despite their efforts and desires, that science blogs are unable to capture a more general audience?"
IMO, most science topics are just too boring for the masses. Unless you talk about a huge medical stem cell breakthrough that made a cripple walk again or something funny like how squirrels suck their own dick most people really don't give a shit whereas everybody will enjoy a mediocre travel blog.

Furthermore, it's really tough to be funny or interesting when writing for the new x molecule that only a handful really understand what it does. Despite this, if you are really talented and offer everything in layman terms I think you can still do it. Take for example thunderfoot. The thing is most real scientists are really good with science and not blogging. :)

"Is community atmosphere really unimportant to STEM minded people?"
If I understand this question properly, no I think all people like to be part of a similarly-minded community!

"Should science bloggers place a greater emphasis in writing for the more technically minded audience they have?"
No! The more technically minded people already get a grasp of what's going on. And for the more technical details they can always check out the corresponding published paper. With people getting stupider and stupider while the scientific knowledge expands, scientists should try to give everything in more layman's terms.

"In what way can steemit play a role in all of this?"
Honestly, dunno. Just another blogging platform I guess, just with a blockchain spin!

"Are projects like @steemstem key to increasing science literacy and getting more people interested in science?"
With no other interested in promoting science posts here on steemit I think the answer to this one is obvious. My only problem is because promotion = money on steemit is that it often attracts people just for the monetary rewards. People that would normally give a jack-shit about posting scientific content and would immediately start posting under a different tag if they discovered it's easier to write about and more profitable. Hopefully, this will improve as steemit becomes more popular and starts to attract more people that genuinely enjoy science blogging

"However reddit is not a blogging platform, and is by and large, terrible for the exchange of ideas and presentation of data."
I would disagree with that. Yeah, it's not designed about blogging but often comments in the scientific subreddits are way way better than the average steemstem blog. Yes steemit is a better platform for blogging but it's the community that is key after all!

I will be back later, work calls. Forgot to be rude, my apologies, next time :)