USCIS just issued a new policy memo titled "Adjustment of Status is a Matter of Discretion and Administrative Grace, and an Extraordinary Relief that Permits Applicants to Dispense with the Ordinary Consular Visa Process."
The memo indicates that adjustment of status will be seen as the exception instead of the rule, and that aliens, with few exceptions, are expected to return to their home country to go through the consular process in order to obtain their immigrant visa.
USCIS website adds: "Nonimmigrants, like students, temporary workers, or people on tourist visas, come to the U.S. for a short time and for a specific purpose. Our system is designed for them to leave when their visit is over. Their visit should not function as the first step in the Green Card process. Following the law allows the majority of these cases to be handled by the State Department at U.S. consular offices abroad and frees up limited USCIS resources to focus on processing other cases that fall under its purview, including visas for victims of violent crime and human trafficking, naturalization applications, and other priorities. The law was written this way for a reason, and despite the fact that it has been ignored for years, following it will help make our system fairer and more efficient."
It is yet unknown whether categories like the National Interest Waiver (EB-2 NIW) will be added to the exception list when adjudicating adjustment of status, or what kinds of RFEs and NOIDs we can expect to see as a result of this policy memo.
What we can say so far is that applicants will be expected to "prove" why consular processing would not be applicable or feasible in their situation.
People choose adjustment of status over consular processing for a few reasons, convenience being the biggest factor. Another factor that people weigh is that consular processing is even more discretionary, and a denial at the consulate cannot be appealed.
For those who were planning to adjust their status, be prepared for higher scrutiny, or even the possibility that you may need to go through a consulate abroad.