We had quite a few discussions about Android app permissions and why these ones are required.
here is below a very good article about it: Use Permissions to Secure Your Private Data from Android Apps
Android Apps Permissions Explained
When you install an application from the Android Market, it will tell you all of the permissions it needs to function. These are important to read as it can give you an idea if the application is asking for permission to do more than it needs. While some legitimate apps often ask for more permission than they need, it should at least raise an eyebrow when deciding if an application is safe and of good quality.
Again, to see the permission given to an application after installation, go to the Market, press menu > downloads, then select the app, press menu again, then press security.
This list was initially prepared by alostpacket who talks about android security in greater detail. The list is not definitive by any means and will be updated as and when it is needed.
Services that cost you money – make phone calls
This permission is of moderate to high importance. This could let an application call a 1-900 number and charge you money. However this is not as common of a way to cheat people in today’s world. Legitimate applications that use this include: Google voice and… (suggestions needed here).
Services that cost you money – send SMS or MMS
This permission is of moderate to high importance. This could let an application send an SMS on your behalf, and much like the phone call feature above, it could cost you money. Certain SMS numbers work much like 1-900 numbers and automatically charge your phone company money when you send them an SMS.
Storage – modify/delete SD card contents
This permission is of high importance. This will allow the applications to read, write, and delete anything stored on your phone’s SD card. This includes, pictures, videos, mp3s, and even data written to your SD card by other applications. However there are many legitimate uses for this permission. Many people want their applications to store data on the SD card, and any application that stores information on the SD card will need this permission. You will have to use your own judgment and be cautious with this permission knowing it is very powerful but very often used by legitimate applications. Applications that typically need this permission include (but are not limited to): camera applications, video applications, note taking apps, backup applications.
Full Article is here: http://techpp.com/2010/07/30/android-apps-permissions-secure-private-data