My perspective is that using NoSQL does not save time in data modeling and migrations. Moreover, one has to pay in increased time for these activities, because
(a) in most cases, data has to follow some model in order to be processable anyway, the question is whether we formally document and enforce it at a relational storage, or leave it to external means (which we have to implement) to benefit from some specifically-optimized non-relational storage,
(b) NoSQL DBs return data (almost) as stored, one cannot rearrange results as freely as with SQL queries, not even close, thus much more careful design is required (effectively, one has to design not only schema but also the appropriate denormalization of it),
(c) migrations are manual and painful, so one had better arrive at the right design at once rather than iterate on it.
That is, of course, if one doesn't want to deal with piles of shitty code and even more shitty data.