Was it good before?
The answer for the above question is "Yes" it was good before. I had friends earning 500-600$/Day just by sitting on their ass, not many developers were developing apps for android. There were Ad networks paying Pay Per Download with other CPM ads which was giving a lot to the developer, many of those ad networks are now closed or changed their policies. The reason for all this is no one but Google itself as they added "No Out of app ads" in their policy which made the ad companies to change their policies.
Is it still good?
Well the simple answer is "Yes" it is still good, but not for everyone, all the good and common ideas are already used by other developers and one needs a good and an unique idea to get their app up on the play store and start earning a good sum.
There are still some good ad networks available which pays a lot and can help you help live a decent life through this. It isn't that great as it once was but still not the worst way to make a living out of it.
What to do?
Google introduced new features in their android phone, there are new things like Google Cardboard, Watches, TVs, etc, which still don't have a lot of developers, developing apps/games for these things gadgets can help the developers earn the way they once used to.
Developing paid apps can be profitable too but isn't the best way as free apps with basic banner ads is much better and more profitable.
Conclusion
With all this I will conclude by writing that Android developing is still profitable if you able to develop a good app which is loved by others(such as PokemonGo).
think there is still money but most easy concept has already been build. so, need a breakthrough idea.
Developing apps for new things like Cardboard, Watches, TVs etc is still a profitable way to earn.
Shot you an Upvote :)Nice @arjeria
Thanks, it really meant a lot.
Thanks, it really meant a lot.