Yes, you can get some Microsoft Office look-alike programs that do 50-80% of what Microsoft's versions do, but you don't get support for those (community support aside) without paying extra. You're not going to run a business on something with no support. When you add support in, it still costs less than Microsoft's Office, but its not nearly such a good deal any more.
Office isn't the only app at issue either... can you run Quickbooks on Linux? (I honestly haven't checked lately, but I'm guessing not.) Can you run your company's tightly-integrated Windows-based ERP system on Linux? The number of top-tier software companies that support Linux is expanding, but it's just not there yet.
Google Chromebooks... the technology is there but they fell flat on their face with the marketing. They have the same app problem Linux does too... there's only so much available for the Chromebook and there aren't enough cloud-based services to satisfy people (at least not yet).
So, until Linux (and Google's Chromebooks) proves to people (especially businesses) that they are ready for the enterprise they'll remain what they are... cool toys for geeks like us.