I do not agree with configuring apache and nginx to do that by default, unless WEI would somehow prevent a server that doesn't understand it from working properly (as far as I can tell, that is not the case). (A system administrator could still change the configuration; this is only about the default setting.)
However, I think the other stuff that you had mentioned would be OK.
Furthermore, a distro maintainer could configure clients by default to disable WEI (or to not include client programs that have WEI).