The direct "select/paste" method is good for sysadmins: you can select a filename and paste it into the next shell command, with a single click.
The problem is, the average desktop user needs "select/copy/paste". A typical word processor session goes like this: select a word, copy it, select a second word, paste. This will overwrite the second word.
With the "select/paste" method, the sessions becomes: select a word, select a second word, paste. Ops!
So, the explicit cut, copy and paste commands are there for a good reason.