1) I think I've got 3-4 updates for Apps every month or so, so it's hardly "never".
2) Indeed. What's more, even if you have viewer for that document type, you may not be able to open it.
For example, I have "PDF Reader" App installed. When opening Outlook PDF attachments, it'll be opened using the App. However when I try to download PDF on the web, IE keep insisting no App for opening PDF installed, and offer to search in MarketPlace. Fine, so I said "go ahead", but then it returns "no App for opening this file type is found". Can anyone figure out how to workaround it? My company relies on PDF a lot when passing documents around to other companies.