I think @Lilienthal's answer may work... but I wanted to hit a few points.
It's not about you, it's about the job
You may win the debate with your job by pointing out that you are very productive at home, and that it's fair and reasonable to leave you there because it's working.
With that said - the strongest arguments are why it's good for your company. I suspect that valid points in this direction are:
You can flex your hours around both company needs and home life.
- it's much easier to jump online at home when you have a sudden idea in the middle of the night,
- or work an extra long shift when you've hit a very productive point
- or be online fast in an emergency, and then make up the time in your personal life more easily when you don't have a commute
Commuting takes time away from doing things (particularly cogent if you're in a high-traffic place)
Your specific responsibilities lend themselves to a lot of solitary work.
Keep in mind that when you work very much alone, you may not see the gaps
I've managed a lot of software development teams in a lot of companies, and the "I'm most productive at home" often breaks down when the manager looks at team productivity. When 1 person writes 1 product, all by themselves, then they can be productive anywhere. But when a team has to collaborate to grow a product beyond a single developer, then this doesn't work out as well.
People talk less and bother each other less when they are remote. That's great if you don't like talking and don't like being bothered. But it's not great if the team is creating a product that doesn't fit together well because people aren't talking enough. One of the problems is, when team members don't share their point of view, there's a lack of consensus, and that leads to a lack of consistency. Each individual is consistent, but the manager often sees the rift between the work of team members in a way the team members do not.
I say this having worked on both side of this debate - I code at home for a personal project, and I really, really hate having to make time for in person meetings on hot topics... but as a manager, I am not happy with my team members taking more than 1 day a week working at home.
So... my other big advice is to be willing to listen to the manager's side of the argument. Maybe you can hear the concerns and find a work at home compromise... maybe you will find that this job is changing in a way that doesn't work for you... but at least you'll know where you stand.
Products can change
The bigger challenge is that just because it worked well for the last few years, it doesn't mean that the product development will continue to work well now. The needs for collaboration grow at the scope of what the product needs to have and the size of the team building the product grow. This as much about how much money the business is investing as anything relating to the technical work itself.
Keep an eye on the climate... it may be that the company culture is shifting and you'll want to look for a new opportunity... or that there are different opportunities in this company that let you keep the work at home option open.