Let the newbies be overwhelmed or be satisfied with their max cost event units imo. You can complete the best story farm map (Base Scramble II) and best challenge quest farm map (Phalanx 2) with only map completion units. You're only using event units to complete more events right now. It takes months to get an army to the point where you can consistently 3 star the hard event maps without spending and actually get min cost event units anyways. In a world of consistent content delivery, revivals provide the missed stuff and allow freemiums and newer players to get that perfect unit then if they want it.

TLDR: New players should get mediocre event units in their first months of play and be content. Veterans need a reasonable schedule of content if you want the game to continue.