Should we have to pay for heroes ?

[Kruize]

Then I think you're not getting the big picture. Maria isn't just a hero, she's a new mechanic of the game which will be closed off to anyone who didn't get her for the first 7 days. Try to imagine if it was "Thousand Strikes" mechanics which is only available for the first 7 days.

Unless of course, they will add at least a blue hero who does the same mechanic, then it will be a different case/

Hell I'd pay another 5 bucks if we could get a purple hero with thousand strikes

And there will be more new mechanics added to the game as it progresses. I don't see the reason why there wouldn't be a blue level healer at some later stage.