That may be true if the definition of selfish was 'what I don't like'. Back to back events allows every single player to have the same opportunity to do what they want to do. A break is a break by any other name, and it denies anyone who wants to play something remotely fresh from doing so so that a small group can play catch up. You can have a brief delay any time you want, just don't play the event.
Nobody is automatically entitled to everything, if you want the event unit and you want to work on your units at the same time, you have to either settle for less CR/Skill, spend some SC, or take a break entirely. Time management is an important part of Aigis, and as I said before, it's not up to the devs to do it for you.
Events are a boon to new player retention. The current event is quite an anomaly, sure, but the majority of events have accessible levels allowing even new players to get a couple drops or stars and get some neat units to kickstart their game, and regularly occurring events shows life and activity.
As for SC, nothing inspires SC purchases like events. When breaks are plentiful premium summon becomes far less valuable because you end up with maxed out teams, whereas events make people think twice about their resources and in turn they look towards premium summon when their team runs into bumpy patches in the event.
Not to mention it's far more enjoyable to summon things when you know you'll have things to use them on.