Guess it depends on the job/role. I was only in the office 2 days a week before this and that was mostly because I had a weekly 5-a-side game half a mile from the office after work on a Thursday.
The vast majority of people I work with aren't in the same office let alone the same country. I've worked for my current boss for 3 years and never met him in person. The one other guy I work directly with I've worked with for over 10 years and never met him in person.
I can't remember the last time I had a meeting of more than 2 people where everyone was in the same room and no-one was on the 'phone. Even when I had a meeting with a few people who were all based in the same office at least one of them would be working from home. If one person is on the phone it's often easier for everyone to be on the phone.
Moving to WFH full time doesn't cost me anything extra. The Internet costs don't go up. Heating won't go up as one of us was generally at home anyway. Given my cycling/running commuting full-time WFH saves me a single £2.60 train journey a week commuting costs (and that's because I went to the pub after 5-a-side).
I wouldn't say no to a chunk of cash or a pay rise to fund a new chair/monitors/etc every few years though.
When/if my 5-a-side game starts back up I'll probably go back to 2 days in the office but that's nothing to do with work, more just a convenience for that.