When importing DICOM data (in DICOM Browser) you sometimes get the hint that certain extensions might be helpful to work with certain data types. I think this dialog is actually counter helpful for the following reasons:

1. The dialog only appears when importing data but it does not necessarily refer to the imported data but to any data that is already in the database. In my case the dialog was constantly bugging me about some old PET data in my DB, which I currently didn't care about, so I learned to ignore it. However at some point I was importing DICOM SEG objects and the hint was actually useful, but I didn't pay attention to the message anymore.
2. The dialog indicates to "helpful" extensions, even though some extension might actually be required (again in my SEG case) to even load the data.

My suggestions:

1. On import only show the dialog for data types actually being imported at that point, not for any other types in the database.
2. On loading show the dialog again for data types being loaded, with the option to ignore the warning for this data type(s) in the future.
3. If an extension is not only helpful but actually require to work with or even load the data, say so. :)