Short answer:
It's always been like this on Mac OS.
While Windows "inspired" itself from many Mac OS concepts, such as drag 'n' drop*, Windows introduced the concept of using Cut and Paste for files, and Mac OS never "borrowed" it.
*note: Some of those concepts may have been invented by
Xerox PARC; I'm not sure. But Mac OS definitely popularized them.
Some people think Cut and Paste should be added while others argue that drag 'n' drop is superior to Cut and Paste, and thus, Cut and Paste for files is unneeded.
Personally, I find that drag 'n' drop + spring-loaded folders is a good way to move files,
but there are cases/situations where using drag 'n' drop is tricky and Cut and Paste would be easier.
For instance:
1) moving files from two locations are "very far apart" (e.g., moving a file from ~/Desktop/folder 1/a/b/c/d/e/f/ to ~/Desktop/folder 2/g/h/i/j/k/l/)
2) moving files from a folder "up" to its enclosing folder (or the enclosing folder of the enclosing folder, etc.)
possible solutions:
1) Deal with it. (or "put up with it" if you're pessimist ;p )
2) Add Cut/Paste.
One method is to use OnMyCommand.
http://free.abracode.com/cmworkshop/
Use OMCEdit to get a giant list of commands. Find "Cut" and "Paste" and add them.