Media Mix modeling involving a lot of data collection and then a lot more number crunching and then comes the actionable insights based on the data.
Let's step back for a minute and think through this in some more detail. The data used to build these models goes as far back as 5 years (if you are using quarterly sales data) or at the very least 1 year (if you are lucky enough to get weekly sales data). So, let's assume on average 2-3 years of data is needed to build a media mix model.
Now, if you were to make decisions based on data which is 2-3 years old, are those assumptions still valid? The data that you are using is frozen in time 2 years ago. Just think through how much has the marketplace evolved since then? There are probably 2 new competitors in the arena and 1 of the big competitors has completely changed their marketing strategy. So, how actionable are the insights which would be derived based on this data? Probably not a whole not.
Thus, the amount of time and effort spend in create media mix models in probably not worth it.
There are some other options of using studies with Dynamic Logic or ComScore which might be able to provide similar insights and represent close to real time marketplace arena.