I think New Orleans - Jacksonville has more to do with connecting the dots to complete the national network. The folks who find that important will find an LA - Las Vegas - Salt Lake City more exciting than just LA Las Vegas, whereas the important multi-frequency corridor focused crowd would find the LA - Las Vegas service more exciting. It just depends on ones perspective.
It also turns out that Brightline is firmly a multi-frequency corridor camper. They, for example, will not touch either the New Orleans - Jacksonville or the Las Vegas - Salt Lake City segments with a ten foot barge pole. Whereas Los Angeles - Las Vegas is in the middle of their sweet spot.
It all depends on ones perspective.
This is not a surprise...you don't build a corridor (which at this stage is generally going to involve over $1bn in capex if you don't already own the line, and several hundred million dollars even if you do) for a small number of trains per day. There's just no way to make the numbers work, and in some respects there's no way to make the ridership work with a big enough distance involved in your major markets.
Taking Miami-Orlando, Brightline is (depending on how you interpret the bond issue numbers) basically paying about $125-150m per round-trip to put such a corridor together and have at least joint control over operations. This is helped by the pre-existence of a good chunk of the infrastructure, but even then a good bit of work was needed WPB-MIA.
I think it is also worth noting, for example, that SLC-Las Vegas has bupkis in the middle. If there were a string of midsized cities (think Des Moines or Omaha) along the interstate between the two that would be one thing, but you're basically looking at a route that cannot support ridership, which is too long for a viable multiple-frequency daylight service (under the best of conditions that's a five-hour run) that would probably cost $5bn+ to set up (and that's presuming no engineering nightmares blow up the cost). Moreover, the market isn't even "that" big...Las Vegas is at around 2.25m, but SLC is only about 1.15m.
This isn't to say (for example) that there might not be room to negotiate an externally-subsidized service which involves running one or two trains per day through (if you could guarantee priority, etc.)...it just isn't going to be Brightline's model.
New Orleans-Jacksonville is a bit better in terms of intermediate markets (Biloxi, Mobile, Pensacola, and Tallahassee are along the line), but even if you magically "fix" the Mobile Bay issue (not cheap), the run to Pensacola (357 miles) is a killer (probably four hours under the best of conditions) and only Tallahassee is of any size along the way.
