Way back when we first started on this iteration of our web panel we had planned to make the domain selector work throughout all the different areas. However, fairly early on we started noticing that it was very confusing to a lot of people, many of which didn't even notice the domain picker over there.
We could have tried to improve the picker itself to make it easier to notice and more obvious to use but there was some divergence within our development team about it. Some of us preferred the 'select a domain' then 'select an action' paradigm because you could select the domain once and then click around making changes (I was in that camp), while others preferred the 'select an action' then 'select a domain/user/etc' paradigm. One problem with the former approach (select domain then select action) is it didn't work well in all areas of the web panel so we ended up with some areas supporting it and others not. That led to further user confusion and made things needlessly complex. Additionally, without having separate choosers for users, mysql dbs, etc the whole concept would never work throughout every area of our web panel.
Some of us tried to hold onto it for awhile but over time as parts of the web panel were redesigned fewer and fewer of them used the domain picker at all until we got to this point where only one remaining part of the web panel used it at all.
Anyway, there's a little history...
- DreamHost Head Honcho/Founder