Actually, The "Main reward" should be the most rewarding while the "Alternate reward" should be something for higher levelled/geared people. As a returning/new player, noone is able to complete the event which gives the most to someone in not TT gear. Sure, getting Hepta gems is nice, but hey there's Octa's you can get from the event as well which you can make into OP Tri or Sqs which new players would definitely find useful in catching up to the higher geared people instead of being secluded in a "Oh you're weak so you can't get the OP stuff anyway" bubble.
Even as a returning/new player, I do agree there could/should be events which are tougher (maybe a HM mode like this time, or you know... something this game has none of... mechanically challenging content! :D Yes. I'm aware everything 1 hits you in the event dungeon unless you can press your Q and E once every 30 seconds), but the tougher content shouldn't give things which new players can definitely use. Let it give TT soulshields, Onyx scales, Grand Celestial steel, stuff from TT and costumes, which the higher end of the community would need, but alts/new players will (at that very moment in time of having close to 0 gear) useless (I'm aware that TT soulshields are OP AF to a new player, but they should still be "forced" to farm something other than materials so the content doesn't die).