Maki is way too smart relative to the other two. Checking status, noticing stat corrections, reading quests... She's just there for exposition and to move the plot.
If Maki was general nice girl I'd be more annoyed by her presence, but she has enough attitude to still be amusing. I'm fine with her being there.
While a story of total idiots stumbling through fantasy world would be funny, doing that effectively would be much harder than simply having somebody in cast actually be sensible.
What were those slimes doing anyway? Do they feed on sweat, dirt, muckus and dead tissue?
Same thing with krakens - why are they always so intent on filling female orifices with tentacles? What do they stand to gain from that, evolutionary speaking?