OK some of you people actually should be ashamed. Great companies and individuals are making huge amount of work and giving it free so they can cover their costs with ads. Like Cartmanuk said in second post if you really like some software and dislike ads that much just buy full/pro/whatevertheycallit version. Google has actually made license that if app has too many and disturbing ads it may get removed from Play so ads shouldn't be much problem, right? Also I bought many pro versions and most of them are around 1 fucking euro including Apex launcher, Amazing Alex and even GTA 3 has been under euro for several times!
Rooting is OK even that manufacturers and providers seem to dislike it
(maybe becouse you can run more advanced programs and customization which isn't good for basic user). It may actually be security thread but if you don't install APK files ouside Google Play and/or trusted source and have superuser app to promp when using root you should be fine. If you are afraid just install some anti virus bloatware and you are safe'rrrr.
Actually it's thread to install APK from random site
even without root so if I were AlanJohn I would double check every installed software what permissions they actually have before some russian knows your mamas phone number.
Got little offtopic but:
If you really really really want to get rid of ads of everywhere then there is better solution than using airplane mode which shuts off every wireless technology on phone. It's called AdFree Android and it just redirects all known adsites requests to localhost which then returns nothing = no ads displayed.
https://play.google.....android.adfree
AAAAND it needs ROOT access