The majority of documents are not shared, they are recorded and preserved. That's why document formats are important. Maybe more than ever.

@Dan, These documents can be created and preserved online too. A document on the web has more advantages compared to the traditional documents which cannot be captured by these formats. I talked about some of these points in one of my previous posts.

http://blogs.zoho.com/general/document-vs-web-document/

RE your statment, "Zoho currently supports these formats (including OOXML)" - exporting Zoho Writer documents to OOXML hardly represents support! 
You can claim support once you have import and export of OOXML across documents, presentations and spreadsheets...considering that you said three months back that "import of OOXML in Zoho Writer is coming soon" and I still don't see it, I am not holding my breath waiting for real support any time soon...

hey, tell techmeme, where you are spending some ad bucks, to stop using the background gray thing... it is just a sign to skim that part and move on, since, you know, we all ignore ads... months have gone by, i never looked at the gray part, went for the stories only

You say Zoho supports pdf but that isn't true, I can't import pdf files using Z.Business or Z.Writer, so what exactly are you saying?

@Don, yes, we acknowledge docx import is taking time. We apologize. Our team is working hard, but project schedules are stubborn, unpredictable things ..

@Michael, we are on it too.

I think, the different formats will remain even if all storage is moved to the cloud, just because the cloud based apps will still need to address data interoperability.

I can’t import pdf files too :(

hey gud stuff indeed.. since the problems wid present formats i can talk about new probs that u may try.. like integrating some word or picture in same board where your docmnt allows image,scribblings all over like a black board.. visit my site http://netaks.blogspot.com

The idea of file format interoperability is still relevant even in an online world. Exporting a document to a file format supports three scenarios:
1) Sharing files with others
2) sharing files between different applications (interoperability)
3) Keeping an independent copy of the file for posterity

Storing documents in the cloud only solves the first of these three scenarios. If I want to open a Zoho document on Google Docs, how might I go about that? As a service Zoho might implement the ability to log into Zoho using your Google Docs account, and maybe Zoho will allow using that information to grab the documents and translate them to Zoho-land, but all you have done is implemented a converter from Google's Walled Garden into Zoho's. At least with File Formats, there is a published spec that anyone can implement and be interoperable with the standard. In this new online world, to be interoperable you essentially need to establish a proprietary format and implement a ton of converters. There are still file formats, they are just now hidden from the user.

And on the third scenario: What do you do, as a user, if Zoho goes bankrupt tomorrow? Do I lose my documents? My only option for backup would be to export them to a file format that is well understood.