Some problems happening often are due to wrong default settings. Some settings are simply superfluous.
As changing default settings within bugfix release (like 1.3.x is for 1.3 series) is considered evil, we had to delay this stuff until we make a bigger release number step - as we will do with the 1.5 release.
change default [new default]
bang_meta  (and later remove it completely) to enable !NoWikiName markup
edit_rows [20?] (reason: with current default of 25 often editor didn't fit into user's windows and users overlooked stuff below editor textarea)
we will also move the buttons to the top
show_section_numbers  (reason: looks ugly and gives information that is often not wanted and more to read)
remove setting and code [new behaviour]
acl_enabled [True] (reason: people tend to use ACLs and wonder why they don't work)
allow_extended_names  (defaulted to 1 in 1.3, but we see no point why anybody would want to set it to 0)
allow_numeric_entities  (defaulted to 1 in 1.3, but we see no point why anybody would want to set it to 0)
replaced allowed_actions (defaulted to ) by actions_excluded (default: ). allowed_actions defaulted to  in 1.3 and was a constant source of confusion as people expected ACLs to determine that stuff, not a seperate setting. As rename and delete of a page are both reversible, we don't need that setting. If someone wants to disallow AttachFile, he can simply add this to actions_excluded.
This will break existing installs! better change the default to include all actions. This will work for anyone.
- Give an example for what you mean by "break". Imho this breaks nothing and people are expected to read CHANGES, btw.
backtick_meta  (defaulted to 1 in 1.3 - we see no reason why `inline literal` markup should not be enabled)
auth_http_enabled - will be handled by new auth setting in a much more flexible way
userprefs item disable / remove
remove allow_subpages (defaulted to 1 in 1.3) and remove code for 0 (reason: why shouldn't we have sub pages? You do not need to use them if you don't like them. We will need sub-items for attachment kind of stuff in 2.0 anyway.)