User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-33754845-20171125151158/@comment-8897944-20171125161653

I think they intended this quest for you to witness how Frenzy Virus works and how it can affect monsters and hunters. Now It has just begun and you will soon experience different monsters in this mode. So, don't get disappointed further.

Rather, your expectations are to be blamed since you said you had high expectations for this quest. If they put Tigrex instead of Congalala, then it would make sense but placing Congalala is a fine choice since it's just there to show you how monsters behave under Frenzy Virus status.