To be realistic, if you had a huge amount of power, it would be pretty annoying to keep hiding it. You'd feel like a weakling if you didn't do anything, plus it would disturb your everyday life. If you wanted to use the power but perfectly hid it, it would be a whole lot of extra work. Takeru's only reason for hiding it, in the first place, was to hide the total level of his power because he fears the world turning against him. That's not any absolute inevitability, though.