94% of all programs won't run properly without those rights.
Unfortunately for the longest time developers for Windows got away with not giving half a shit about security. To make matters worse, when MS finally decided to tighten the screws, they went overboard by a long shot. You cannot even install a simple program without elevated rights.
Millions of corporate PCs run with users having user-only access, and it works fine. Browsers, media players, CAD programs, Office suites, all work fine.
In my experience the only programs that "have" to run admin rights are:
-Low level tools eg: CPU-Z. This is expected as it needs to load low level kernel drivers.
-Installers. This is expected as they are writing in common subdirs. In Linux you need elevation too. "Sudo apt-get install"
-Old programs that were coded without any thought to admin rights.
A lot of times the old programs can be worked around. Either the users need write access in the program's "Program files" subdir, or users need write access to an HKLM registry key. These are the result of sloppy coding.
Since Vista was introduced 10 fucking years ago applications have been better coded at not requiring admin access at run time unless absolutely required.
With Windows 7 Microsoft transparently hid the UAC dialog's for a lot of system tasks. eg: If the user is admin, and wishes to set the clock, they can without UAC prompt.
UAC is also easier than sudo or OSX. You just have to click the fucking yes button, you don't even need to enter your password.