Architecture is a broad field, with many niches, specialties and corollaries. Same goes for an architecture education, so it’s hard to generalize.
The choice between the BArch and the BA/BS+MArch is purely personal. Some high schoolers are ready to make the commitment that the BArch demands, and are able to start successful careers as architects in their 20’s. Some – for various reasons – e.g. interests in other fields, not enough information about what architecture entails – would rather use their undergraduate years exploring a range of academics. Some of my son’s colleagues in his MArch program previously studied and/or worked in different fields altogether, like tech, sociology, engineering.
The cost difference between the two routes can be substantial. Though some funding is available, the MArch tends to be an expensive degree (relative to architecture salaries) and it’s important to take this into consideration when choosing the undergraduate school.
The downside of the BArch is its high drop out rate, I think due to a poor conception of what an architecture education entails. The artsy, creative types find the tech/science aspects daunting; the tech/science types find the studios, especially the critiques, stressful.
My son, who graduated from Williams with a dual degree in art studio and art history, considered both a career in museum work and architecture. After graduation he worked for a couple of years in the marketing department of a design-focused architecture firm, then got his MArch from Cornell.
Cornell is the only Ivy that offers the BArch. Yale, Harvard, Penn and Columbia as well as MIT, Berkeley, WUSTL, Virginia, UMich and other high profile schools of architecture only offer the MArch, though they all have some permutation of a BA/BS that may lead directly to the MArch (though not necessarily at the same institution).
Yes and no. I would concur with @bgbg4us that firms tend to hire locally, some to the extent that they only hire from their preferred schools (often the partners’ alma maters). My observation is that summer internships and connections made through professors and visiting critics are the most critical element in landing a post-graduation permanent job.
It’s quite common for BA/BS grads to work in architecture (for example in marketing or the model shop) for a year or two before heading back to school for their master’s. It’s also increasingly common for BArch holders to layer on an MArch later in their careers – for further technical or design training or just for a more name-recognized degree.