You had 8.0.2 installed? Each update fixes bugs, adds new features, tweaks things, etc.
Plus, there are
SECURITY FIXES. Once an update is out, Apple publishes a list of fixes. It's important to update, as information on how to exploit the older versions is now in the public.
Here's some security fixes you don't get by staying on 8.0.2:
8.1 security fixes:
CVE-2014-4428: A malicious Bluetooth input device may bypass pairing
CVE-2014-4448: Files transferred to the device may be written with insufficient cryptographic protection
CVE-2014-4449: An attacker in a privileged network position may force iCloud data access clients to leak sensitive information
CVE-2014-4450: QuickType could learn users' credentials
CVE-2014-3566: An attacker may be able to decrypt data protected by SSL
8.1.1 security fixes:
CVE-2014-4460: Website cache may not be fully cleared after leaving private browsing
CVE-2014-4455: A local user may be able to execute unsigned code
CVE-2014-4461: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-4451: An attacker in possession of a device may exceed the maximum number of failed passcode attempts
CVE-2014-4463: A person with physical access to the phone may be able to access photos in the Photo Library
CVE-2014-4457: A malicious application may be able to launch arbitrary binaries on a trusted device
CVE-2014-4453: Unnecessary information is included as part of the initial connection between Spotlight or Safari and the Spotlight Suggestions servers
CVE-2014-4452, CVE-2014-4462: Visiting a maliciously crafted website may lead to an unexpected application termination or arbitrary code execution
8.1.3 security fixes:
CVE-2014-4480: A maliciously crafted afc command may allow access to protected parts of the filesystem
CVE-2014-4481: Opening a maliciously crafted PDF file may lead to an unexpected application termination or arbitrary code execution
CVE-2014-4455: A local user may be able to execute unsigned code
CVE-2014-4483: Opening a maliciously crafted PDF file may lead to an unexpected application termination or arbitrary code execution
CVE-2014-4484: Processing a maliciously crafted .dfont file may lead to an unexpected application termination or arbitrary code execution
CVE-2014-4485: Viewing a maliciously crafted XML file may lead to an unexpected application termination or arbitrary code execution
CVE-2014-4486: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-4487: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-4488: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-4489: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-8840: A website may be able to bypass sandbox restrictions using the iTunes Store
CVE-2014-5352: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-4491: Maliciously crafted or compromised iOS applications may be able to determine addresses in the kernel
CVE-2014-4495: A malicious application may be able to execute arbitrary code with system privileges
CVE-2014-4496: Maliciously crafted or compromised iOS applications may be able to determine addresses in the kernel
CVE-2014-4492: A malicious, sandboxed app can compromise the networkd daemon
CVE-2014-4493: A malicious enterprise-signed application may be able to take control of the local container for applications already on a device
CVE-2014-4494: Enterprise-signed applications may be launched without prompting for trust
CVE-2014-4467: Visiting a website that frames malicious content may lead to UI spoofing
CVE-2014-4465: Style sheets are loaded cross-origin which may allow for data exfiltration
CVE-2014-3192, CVE-2014-4459, CVE-2014-4466, CVE-2014-4468, CVE-2014-4469, CVE-2014-4470, CVE-2014-4471, CVE-2014-4472, CVE-2014-4473, CVE-2014-4474, CVE-2014-4475, CVE-2014-4476, CVE-2014-4477, CVE-2014-4479: Visiting a maliciously crafted website may lead to an unexpected application termination or arbitrary code execution
8.2 security fixes:
CVE-2015-1063: A remote attacker can cause a device to unexpectedly restart
CVE-2015-1065: An attacker with a privileged network position may be able to execute arbitrary code
CVE-2015-1061: A malicious application may be able to execute arbitrary code with system privileges
CVE-2015-1062: A malicious application may be able to create folders in trusted locations in the file system
CVE-2015-1067: An attacker with a privileged network position may intercept SSL/TLS connections
CVE-2015-1064: A person with physical access to the device may be able to see the home screen of the device even if the device is not activated
Sources:
https://support.apple.com/en-us/HT203119 (8.1)
https://support.apple.com/en-us/HT6590 (8.1.1)
http://support.apple.com/en-us/HT204245 (8.1.3)
https://support.apple.com/en-us/HT204423 (8.2)