I've found that quotes are often misused by those whose who use them to argue from a position of authority rather than to provide depth or insight into their position. A typical example is a person who quotes the Koran or Bible to back up their views because they believe that the religious texts are the word of God and therefore are automatically correct and supersede all other opinions.
I don't see any reason why a person shouldn't quote a particularly pertinent section of a sutta if it helps convey a concept or idea to another. There are times when someone has already explained something extremely well and it would be silly not to quote them when the opportunity arises.
Being able to quote suttra is one thing. It's the easy part. The other thing, understanding the suttra you quote is something else entirely. Understanding is the hard part. Understanding is what supports practice and practice is what leads to enlightenment.
That said, there are times when a relevaant quote is helpful, but I don't think those times are as common as someone needing to demonstrate understanding.