However, I fully believe I can build a home office that's better (for me) than most employers can, at a fraction of the budget. It's a more efficient solution than a centralized office, but it's coming out of my pocket and not theirs, so it hurts me more.
Of course, your direct complaint seems to be the square footage, not the hardware (desks, etc). That's a tougher one to solve for, because larger square footage is opex instead of capex, and it'll be more challenging to get your employer to part with opex dollars.
(Yes, there are larger apartments, but they are somewhat rare. Maybe this will change!)
In NYC, 2/3 of households rent, according to a 2017 government survey: https://www.census.gov/programs-surveys/nychvs.html.
Not to take away anything from your point: it is an interesting thought experiment. For people who have an intuitive understanding of opex v capex, it's also a very convincing argument for owning your apartment (since your mortage "feels" like opex, but is actually capex, and it's always better to spend capex dollars).
This is especially true in markets like NYC, where you might never reasonably expect to pay off your mortage (since it's a coop, or the principle is 10+ years of untaxed salary).
Would it matter the interest/equity proportions of the mortgage payments? Also what about the other costs associated with owning the real estate (taxes, maintenance)?
Interest in most loans is front-loaded (i.e. your payments are mostly "interest" rather than equity in the earlier parts of the loan), and you can write off payments towards mortgage interest on your taxes in the US. So, while interest is technically opex, the government currently allows you to treat it as capex, tax-wise, because they want to subsidize home ownership. If you aren't in a top income bracket, this won't affect you much.
Other costs are tricky because, in competitive markets at least, taxes and maintenance cost are usually priced into your rent, so you're usually paying them whether or not you own your home.
The big difference is that when you own the home, the taxes and maintenance costs arrive all-at-once (when your home floods, or the boiler falls apart), rather than amortized over years of residency. That's why mortgages are almost always "cheaper" per-month than rentals: rentals price these costs in, mortgages do not. If you have a good chunk of liquid savings and can afford good insurance, exposing yourself to occasional all-at-once payments are not very risky.
Also, you can eventually and typically write off big expenses (if you rent out part of your home, or sell it later and keep good records). https://www.nolo.com/legal-encyclopedia/what-home-improvemen...
I don't think your problem with quitting has anything to do with WFH policies.
If you don't have to go in everyday, the possible commuting distance increases massively. Before the virus, I worked from home and my commute was 160km twice per week by high speed train.
Take a map around the office where you work. Look at the kinds of home prices you can find an hour out. See how much closer you can be to nature or other particular amenities that matter to you. Would you like to have those with zero total change to your commute time?
Sounds pretty nice to me.
People like their socialization at work. Many also like living in the city anyway (granted, most of my colleagues are young and childless). And outside of extreme cases like SF, a tech salary is enough to rent a decent apartment.