What you say is to some extent true. In other City Builder games, you might have to cope with disasters - which are unpredictable and often with no notice. Every game is different. In this game, you must make choices about how you intend to play the game. It is not up to the game designers to accommodate your choices.We can probably argue for months what is a strategic vs a tactical choice.
Conceptually, I feel that there is a world of difference between strategizing to develop a city and conquer known continents and tech trees, and reacting to what the devs choose to put in an event (unpredictable and often at short notice).
When it comes down to it, participation in events is likely monitored by the game designers. They know participation levels, but they also know things like diamond usage - and purchases. The goal of the game designers is to generate revenue for Inno. Poor design choices will result in players leaving the game and lost revenue. Good design choices will result in continued player participation and increased diamond purchases.
I would posit that the increase in events is a direct result of the metrics from past events.