I understand that it makes sense to have some settings just per blog.And some global settings that blogs can override.
But i think we should also look from the reverse perpesctive i.e:

I want to "definitely" disable/enable certain features across blogs, but the problem is, my global setting might be overriden by a blog setting (:cache setting), or it might not even be available globally (may only be a per-blog option : subscriptions, custom css), or i do not know even if this setting is on/off in my blogs.

The above is not an issue if you have 2-3 blogs, which is usually the case.However if you are dealing with 10+ blogs like me, it's a pain, i cant even imagine someone running a "userblog" with hundreds and thousands of.

I am not being ridiculous, it makes sense right ?

PS: in my case i wanted to turn off subscriptions across blogs, but i dont want to go one by one to all of them.It'd be cool to have one rule to rule them all, pretty much like !important in css in terms of functionality.