Orchid, your co-worker reminds me of a young woman who was my first intern, and later my first employee.
When I first me her, she was a college student, living in a dorm. On graduation, she and her boyfriend moved into an apartment in an old house, which was just off campus, as he was still finishing his MBA. So nothing seemed odd to me about their housing choices at that time.
But then he got a job with a big corporation that has multiple office locations and was sent to Atlanta. Immediately they got engaged and started gearing up for her move down south after the wedding.
She told me they were looking at large 4-5 bedroom homes with big yards and multiple bathrooms - which really took me by surprise. But her explanation of why "kinda sorta" made sense: The corporation he worked for would be moving him every few years, and their relocation staff suggested this sort of home, saying it was always going to appreciate in value, and would always be easy to sell.
Clearly it would be a lot more home than a startup DINK (dual income no kids) family would need.. and I agree about the trouble to clean it, not to mention needing to furnish it.
But I also understand the concept of buying a home you know will be easy to sell -- if you know that you will be relocating every few years.
As for us, we downscaled to a smaller home as soon as our youngest graduated from college. By then the dog had died as well, so in addition to no longer needing 4 bedrooms, we also no longer had a need for a fenced yard.
These days Steve and I occupy the main floor of a duplex townhome, living all on one floor in what is probably no more than 800 square feet. Our space has 3 bedrooms, but we use two of them as offices. (In reality, we also have a fully finished lower level, with two more bedrooms, another bath and a family room. But I might as well rent them out -- as we never go down there.)
I think this is a good amount of space for our needs. I don't think I would want to go smaller than this - being as we work from our home so Steve and I are essentially together 24/7. I find it is a "good thing" to have enough space so that we don't feel like we are always in each other's pockets, so to speak.