Why needs to root the French Archos 101 G9 tablet since you can check option to allow the tablet to install non-Android Market applications .apk file?

Why needs to root the French Archos 101 G9 tablet since you can check option to allow the tablet to install non-Android Market applications .apk file?
Enable it under Setting -> Applications -> Unknown sources: Allow the installation of non-Android™ Market applications.

Online manuals: http://www.archos.com/manuals/A101G9_EN.htm

Place to download apk files:
#1. http://apk.tw
#2. http://www.androidai.com
#3. http://www.androidapk.net
#4. http://www.mobile01.com/topiclist.php?f=423
#5. http://gphonefans.net/forum.php?gid=10
#6. http://android.cool3c.com
#7. http://www.coolapk.com
#8. http://cn.androlib.com
#9. http://filecrop.com

Please go to Android Market and find the AppInstaller and Apk Manager in order to install the download ???.apk as Apps on the tablet.
https://market.android.com
AppInstaller: https://market.android.com/details?id=com.funtrigger.appinstaller&feature=related_apps#?t=W251bGwsMSwxLDEwOSwiY29tLmZ1bnRyaWdnZXIuYXBwaW5zdGFsbGVyIl0.
Apk Manager: https://market.android.com/details?id=com.magmamobile.app.apkinstaller&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5tYWdtYW1vYmlsZS5hcHAuYXBraW5zdGFsbGVyIl0.

http://www.dropbox.com