If you're relatively handy, a lot of what OP paid for can be DIY'ed. I would have never paid a contractor to do all of that. Probably just the electrical. Especially the Tuff Shed structure. Those things are dead simple, marketed at DIYers, and can be finished in a weekend. Insulation, drywall, trim, and flooring is also child's play. OP could have easily cut the project's cost in half if he wanted to.
Yeah I had the same thoughts about what they chose to DIY vs hire out. Insulation is so simple, and trim can be done at your leisure. But thats also not likely to save much overall since the contractors also know how simple those are.
You're missing the important part: doing all of this WITH A ONE YEAR OLD CRAWLING AROUND AT HOME. You can get things done, it is just an order of magnitude longer that it would take without kid(s).
Author here. I have heard this complaint from others before. If you live in an area where it snows I am assuming this would be a pain. But a 20 foot walk to my house is not a trek. If I was in an office the bathroom and coffee would be farther away. Honestly I like the outside part of the trek, it is a nice change.
The Coffee issue is easy to solve, just bring a pitcher of water with you in the morning to pour into the coffee maker - it's what I did when my home office was in a spare room above the garage. The walk from his back yard to the indoor bathroom is probably shorter than the walk he'd have in any office.