I don't pretend to know DL's intent; however, for me, as a beginner, it is much easier to learn "voy a [any infinitive] than to learn the future tense for every verb. I will focus on learning pure future tense after I can express myself in past and present - and by then I will be studying more advanced courses than is offered in DL.
A previous commenter answered this question, so I'm answering using their knowledge and not necessarily out of my own personal experience--the difference seems to be that "colocar" means something is being placed in a specific location whereas "poner" means it's just being thrown in your suitcase, in a sense. I'd see this as the difference between the verbs "put" and "place" in English.
I answered "I'm going to put it into your suitcase" and duolingvo didn't like the translation :(