Generally end users just press yes to all privilege questions, so there is no point of asking, as its just one useless dialog that bothers the end user experience. There is no point of asking question that users dont understand anyways (well yes 1% do understand, but do you want 1% to spoil the experience for 99% of other users). Those 1% are able to do their own hardening in developer mode anyways (as you can freely tweak android app permissions from commandline).