Zwift, being a tech company, is probably challenged to attract and retain skilled employees - which is a scarce resource. If you’re ace at what you do, would you work for Microsoft, Apple, Google, Zwift, etc.? Why choose one over the other?
Refurbishing office premises may appear expensive - obviously depending on what you do - but consider the time, effort and money spent on recruitment and retention of tech talents. I am sure the number crunchers and bean counters at Zwift easily can justify their office upgrade if they believe it will increase their probability at attracting employees, getting positive PR, wooing investors, partners, relevant stakeholders, etc. I think @jfranci3 hits the nail on its head: The offices are not just for its employees, it is equally (or perhaps more) a marketing effort of sorts.
If you visit any other attractive company, I am quite certain that you will find some variation of the Zwift offices. For instance, from what I’ve seen of TrainerRoad’s offices through Instagram posts from @Nate_Pearson I would think that TR too have a relatively nice office for its employees.
I say fair play to Zwift.