Not sure why it was removed, but how would I go about adding the "assets" bundler group back into my Gemfile, and having it only be included for asset precomplication on deploy (as well as development etc.)? Basically, to recreate the functionality that was already present in Rails 3.
My rationale is to reduce runtime memory usage, since the gems I would put into that group are only really needed during asset precompilation.
Also, is there any inherent reason why this would be a bad idea? I deploy to Heroku, in case that makes any difference.