Seems you didn't like my rather open-minded answer... :)
Let's talk serious.
1) I'd be very much interested in writing good elaborate answers. I actually have done so on numerous occasions. You know what? People don't read them.
Can't tell you how many times I wrote single-line answers to get numerous votes and immediately after adding "substance" as you call it the voting ended up abruptly.
I actually learned this tactic from seasoned high-rep users (40K+) on SO.
People just don't want to read the stuff. I can't do anything to change them.
If I see folks don't read my answers, I have no motivation of writing them really.
At the very least I can amuse myself by seeing numbers tick (rep growing).
2) The other reason is that by the time you finished writing an elaborate answer there will be 10+ single-lined answers voted up to the heaven. Nobody will notice yours.
Who's to blame if the site is all about being the Fastest Gun in the West?
I suppose the blame is partially on the site creator.
There have been COUNTLESS proposals on how to change the operational model to realign to the quality rather than to quantity and mass. They were all turned down. The creator is very stubborn and doesn't want to listen to input.
Even I proposed an improvement - lock out answers display for the first N minutes to give everyone sufficient time to contribute quality answers - I got laughed at.
(Just tried to locate that old question of mine - seems it was deleted. So much for user voice.)
That other trick with limiting reputation growth to 200 per day only results in newcomers desperately trying to reach the elder by contributing an insane amount of answers, quality evidently suffers here.
You can also see with all that stackexchange expansion that the creators do not concern themselves with the conceptual problems - it's now all about growth, expansion, consumption of markets, going public and so on.
At that time I'm starting to hope somebody will start a different Q&A site - with the right priorities and with the right attitude.