Auto First Class Upgrades for Gold
 

There are often empty first class seats on flights.

As a GOLD member, they've never once upgraded me from main cabin select or otherwise when there are empty seats. I feel like most other airlines bump up their preferred members so those seats don't go empty.

Anyone else noticed this policy?

you have to pay for upgrade if there is spot available when you check in, regardless of your status. But if you have status, you can have earlier access to the upgrade if there is space available.

If by "notice this policy" you mean that they very clearly state that VX Gold members don't get free upgrades to first, then yes.

Most other airlines in the USA, yes, give the F cabin away on most routes to elite flyers. VX has made a business decision to always have the front cabin monetized (except in irrops/oversell), which is the same policy as many of the worlds' airlines.

It is not an unwise business decision. VX already gives "us" the chance of a free UG into a seat with unlimited food and drink and IFE.

Something else to consider is that VX's F product is both more limited and far more improved than a "normal" F product (while VX's Main Cabin Select is on par with most airlines' F product in terms of seat pitch).

In a sense, VX offers a "true" F product and (with a few exceptions) other airlines do not. For a handy example, on the A320, Virgin's seats are as follows (pitch/width/number):
First: 55"/21"/8 seats
MCS: 38"/17.7"/12 seats
MC: 32"/17.7"/129 seats
Total: 149 seats

For Delta, same plane:
First: 36"/21"/12 seats
"Comfort": 34"/17.2"/18 seats
Economy: 31-32"/17.2"/120 seats
Total: 150 seats

United, same plane:
First: 39"/20.5"/12 seats
"Economy Plus": 35"/17.7"/42 seats
Economy: 30"/17.7"/96 seats
Total: 150 seats

Jetblue, same plane:
Even More Space: 38-39"/17.8"/42 seats
Economy: 34"/17.8"/108 seats
(I think this is slowly being reduced in line with other airlines)
Note: On Jetblue's Transcon services, they have a First/Suites option.

American does not fly the A320. They do fly the A319, however:
First: 38"/21"/8 seats
Main Cabin Extra: 34"/17.7"/18 seats
Economy: 30"/17.7"/102 seats

Southwest has one class of service and so I'm not including them in this.

TL;DR: Virgin's Main Cabin Select (which auto-upgrades do trigger) is equivalent to regular "First" on any of the main US carriers' normal services. Virgin's First is not quite on par with the Transcon First/Business services on their premium products, but Virgin offers their First on every route and I don't think the other airlines are particularly keen on handing out free upgrades to the "better" first.

To put this in more blunt terms, the reason most airlines will comp folks into First is that First isn't really First. Conversely, Virgin's First is a "proper" first.

I'd disagree with this statement emphatically. While the legroom may be the same, having 3 across (and on most VX flights the middle seat in MCS is occupied, at least in my experience) is much, much less comfortable than the 2 across seating that you'd find in F on other domestic carriers. Having other peoples elbows or bodies infringing on your space, which happens in MCS but not other 2 across F, is pretty uncomfortable for me.

Personally I think the MCS product is overpriced for what it is. Getting row 9 in MC is a much better value.

I agree with the comfort (width) but the MCS product is what VX gives elites for free, if available. And, the F&B selections are better than a lot of the dreck that many carriers serve in F. So, back to the OP, it isn't as if VX doesn't provide an upgrade into something.

I really don't want to sit in MCS for more than a few hours, and I hate having to go from row 3 to the rear lav. On the other hand, I'd rather sit in MCS than any other carrier's expanded legroom Y section.