As a SMART PERSON let me explain to you DUMB PEOPLE that this year's Summer roster is just a content buffer.
They loaded the roster with the second-string Summer choices so they can reserve the bigger Summer characters for next year's Summer when the future of the game is uncertain and they might need a boost in revenue following the conclusion of Part 2.
You'll get your Summer Louhi/Nitocris Alter/Egao/Caren next year because that's when Lasengle will absolutely need them.
Also, a little more of my INT for you simpletons: Odysseus would be a kino Grand Rider.