Some blocks will require support from the theme to be displayed properly on the front end, both in terms of theme_support as well as loading relevant styles (gallery columns) that we so chose to not render inline.

Extracting from #422:

there’s been some chatter about how themes could define support for blocks or block controls (like image full bleed). maybe something with that and add_theme_support ?

seems we might need to allow a base stylesheet for a block, plus editor and/or front-end specific extras

So, this likely means that more blocks will need to register themselves on the server side, and we'll need to allow the register_block function to accept values for these stylesheets.

Edit: also worth considering: themes themselves will probably want to add styles for individual blocks.

See also #289.