you are right. However, one of the main points tested during case interviews is the candidate's ability to be efficient in his/her approach. Of course the entry mode influences the financials. Nevertheless, it is much more efficient to get a quick understanding of whether entering the market harbors enough value potential to outweigh the corresponding investments or not. If it is the case, then we already know that it makes snese in principle and, hence, have already answered part 1 of the questions in a much more time efficient manner than if we would boil the ocean and repeat the analysis for every possible mode of entry. This ability to identify the most important bits of analysis quickly and getting a high level undertanding of what the answer will be is a core quality that MBB are looking for.