Yes not wrong but you will lose the extra bit of information provided by -ki-. When the object infix is used we know what class the object receiving the action is from.
Yeah, but ... the word chakula comes right after. That's clearly the object.
Of course if you consider the whole sentence it is clear what the object is because of "chakula" . I only meant in the context of only the single word "wanapika" vs "wanakipika" . When looking at only "wanakipika" you can know what class the object is from but you lose that information if you drop the "-ki-" to "wanapika". I hope this is clearer.