By obtaining a visa for France the would-be traveller gains border-less access to all of the the 26 Schengen states (countries signed up to the Schengen Treaty).
With today’s heightened risk of smuggling, drugs/people trafficking and terrorism, it has become increasingly important for consulates to thoroughly vet all visa applicants. Such checks are to ensure that the visa applicant is legally resident, that they can financially support themselves throughout their trip and that they have the means and good reason to return their current country of residence.
In addition to the ID and status checks, for many applicants, the Embassy/Consulate also require a complete detailed itinerary that shows every stage of the proposed trip outlined in their application. Not being able to produce evidence of any aspect of the above will almost certainly result in the visa application being rejected, refused or delayed.