I didn't dropped any keywords yet but I've been pretty close to that. 
See http://bugs.gentoo.org/show_bug.cgi?id=81702 for more info.

I think the reason people drop arches is laziness of some arch herds. 
C'mon people, how hard can it be to see if it builds right on your arch?

Jason Wever wrote:

>Hi All,
>
>I'd like to ask that you all take the time to review the keywording
>policy in the Developer Handbook.  In particular, I'd like to draw
>your attention to the section on "Upgrading Ebuilds" [1].
>
>People have been getting good lately at either dropping keywords for
>no reason and/or failing to notify or file a bug with the arches
>dropped as to why.  Chances are if you have done this for SPARC, you've
>probably heard from me already.  If not, GenBot is on his way to your
>location as we speak ;)
>
>Now back to your regularly scheduled hack-fu...
>
>[1] -
>http://www.gentoo.org/proj/en/devrel/handbook/handbook.xml?part=2&chap=5#doc_chap5
>
>Thanks,
>  
>