NDOT has other priorities in the north to address before working on that (namely a revamp of the Reno Spaghetti Bowl and addressing traffic/capacity concerns on US 395 north of Reno).
It's interesting that NDOT is still dumping money into that interchange. I get that I-80 is an important national route, but at the end of the day, we are talking about a metropolitan area of less than 500,000 people.
With that mentality, why did NDOT bother dumping money into a freeway around Carson City when it only serves a metro population of less than 60,000?
Well, it is the connecting point for the major E-W and N-S corridors in the region -- and if it's getting congested during off-peak hours, that points to a design that is inadequate for the traffic flow. Since N. Nevada is a relatively fast-growing area (within Reno metro as well as the various exurbs to the east and south), attending to chokepoints before they become more of a problem than they currently are seems to be an appropriate use of available funds; the "band-aid" approach applied to the interchange in the past clearly hasn't cleaned up the issues. If the funds are indeed available, better to utilize them in short order rather than wait until inflation eats away at their purchasing power -- particularly with a project that requires multiple structures.
The "still dumping money into that interchange" comment is questionable... That interchange was originally built circa 1970, and is substantially the same now as when it was originally built. The only real improvements have been braiding the westbound I-80 ramps between 4th St and US 395 in the mid 2000s (previously a VERY short merge) and splitting the northbound US 395 ramp to I-80 into two during the northbound 395 widening project circa 2010.
Sparker is correct in that the Reno area population is expanding, particularly in the north valleys (up US 395 towards Stead and Cold Springs, as well as out the Pyramid Highway corridor) and most of that traffic funnels through the Spaghetti Bowl. The interchange has design flaws that don't allow address current traffic demands. Southbound backups during morning commute as lanes drop through and downstream of the bowl, and northbound backups happen through the bowl due to weaving. I-80 eastbound has backups in both morning and evening rush hours (as well as other off-peak times). It needs a revamp now–NDOT is just beginning the scoping phase and aren't even projecting to finish environmental review until 2020...
It seems to me that they've been re-aligning that interchange since the 1980s. Fairly sure that I-580 south of there was, at one point in the 2000s, the widest freeway in Nevada. I mean, at a certain point, develop a plan and implement it, sure. But I could easily see another 80/395 project spiraling into a multi-billion-dollar Project Neon-type behemoth… for a city of a half-million people.
As for the comparison to the Carson City Freeway, I think that's apples and oranges. Clearly, there's a need for the West to catch up on mobility in its formerly-rural corridors, and 395 is high on that list. I guess I'm just saying that as far as Nevada's spending needs goes, a $1 billion or $2 billion could be better spent improving rural safety, extending 580 to Gardnerville, improving access to Spanish Springs Valley, or even building 100 miles of high speed rail between Reno and Las Vegas than reducing congestion at the 80/395 interchange.