I don't know when the Mozilla Foundation will finally get this straight but here it is again - some extensions really matter! For those upgrading to Firefox 3.0, there will be grave disappointment when they discover certain popular and key extensions are not yet updated.
I get the philosophy of having a lightweight browser where you add the features you want through extensions. However, some extensions are so popular that they take on the same weight as a standard feature. Ultimately, if the extension is not ready, then the whole software package is not ready. You can't act like extensions and plugins are part of the rich universe of your product and then ignore them when you launch a new version of that product. When the extension doesn't work it is the same as having removed a feature.
Take IETab. This extension is not only great to have, it's essential. There are still a great many websites that are built for Internet Explorer and won't render or function correctly in Firefox. IETab elegantly deals with this problem by allowing Firefox to use the IE engine in a tab. Other extensions simply launch IE which is not what you want when you open a bunch of tabs. This is a critical feature for Firefox to be useful outside the closed world of Open Source people who have disdain for Microsoft. Yet, IETab is not ready for download into Firefox 3. Heck, I can't even find it in the Add-ons site anymore. It only seems to exist at the development site, Mozdev.org.
Every time Mozilla launches a new version of Firefox or Thunderbird, we go through this. Half of the important extensions don't work or are unavailable from the automatic upload service. This is too consistent a problem to be accidental.
It calls into question the whole idea of community development. I'm not criticizing the author of IETab. They have better things to do than keep up with Mozilla. It's up to Mozilla to make sure these important extensions (really features) are available. If the community can't do it then Mozilla has to. This is the millstone around the neck of the Open Source community - inconsistent support for vital features. If Mozilla has to rely on people who do this as a hobby for their product to be functional, it will never be truly competitive.
Since I hate complaints without solutions here's what I suggest. First, find out what extensions are important to the majority of users. These are now features. Whether you make them available as a built in feature or an extension doesn't matter. They just have to be available. Second, design Firefox to insure backward compatibility with older extensions. A lot of extensions won't load because they say they only support the last version. My guess is that many of these extensions would run fine if it weren't for the version check. Maybe the solution is as simple as a override on the version check for a particular extensions.
Finally, stop releasing product until you have tested the critical extensions. Recognize that your work is not done until the extension maker's work is done. It would also help if the latest version is available for automatic update. Sometimes extensions are available on the author's website for quite some time before they hit the automatic update facility.
Luckily, I backed up my extensions and kept FireFox 2.0 around. I'll stick with that until I know all my critical extensions are updated. This is not the way I would have liked it to go.