embedded images in a forum post will immediately follow each other. It might be worth considering adding a small gap, maybe only a few px, in between two image tags where one directly follows the other.

you can add double linebreaks between images, which will add some empty space. i've seen people use the lack of padding to tile things, which is useful especially in sigs

szy is right on the money, the lack of spacing is to allow for things like that

i'm not sure how the markdown styling handles it but in that case it wouldn't make sense for images in different paragraphs to be touching one another, bbcode and markdown aren't equals and exist in different tiers of purpose in my opinion which is also why i decided to offer both

with that said i have previously thought about introducing a [p] bbcode that essentially just functions as a <p> paragraph tag, but for reasons that'll be a little while. we're not there yet but eventually bbcode should be able to do everything markdown lets you do, but not the other way around since i see bbcode as more general purpose multimedia postings whereas markdown is more focused on writing a big wall of text