I think running application over the web/cloud/internet is super useful especially now that we typical carry multiple devices and use multiple computers. Syncing data across these different physical devices can be real pain so having a centralized service somewhere where there are paid professionals handling the IT work behind-the-scenes is wonderful thing for consumers.
However, there is a cost to building web applications is sometime overlooked even by the companies that built them. The Web has often been touted as making software cheaper (no more packaging, update/patch disks and store shelf space to pay for!) and easier to build (HTML is simple!), but as any modern web application developer can tell you things are never that easy. Maybe during the first few years of the web where everything was basically static HTML and images it was true, but now the cost of software development for web applications goes way beyond what it used to cost to build shrink-wrap software.
This cost is maintenance. Shrink-wrapped software is run and managed by the consumer that buys it. Even if at some point the software is not supported, the user can still run it themselves. Online web application is not the same. There is never an end to an online application unless the plug is pulled and it stops completely. Engineers can't deploy version 1.0 and then move on to the next version because once it is available developers often become the system admins keeping the software alive. Companies often forget this and as soon as a version is done they jump on to the next "big idea", but the engineers aren't done with that version. Their work only increases following the launch.
Does this mean that cloud computing should be avoided? Absolutely not. Consumers needs to be a little smarter in what they chose to use. With cloud computing, it is the data that is more important to keep alive and not those WordPerfect install disks. So find companies and products that makes it clear what their data export policies are. Do they support data libration or are they a closed garden?