What is the reason for halving the rewards? What is the reasons for halving the rewards?

Why not, for example, let the reward be always the same and the amount of currency always growing? Are the reasons technical or just purely ideological?
Because the block halving incentives getting into Bitcoin NOW, rather than later. Early birds take more risks and get more rewards. Otherwise the network would have problems getting enough miners involved in the first place.

Asides that, there is a concept of inflation and deflation - we have already experienced the first one, so we might as well try the latter one.