The only problem is that for the people buying the groupons. I only try to limit myself to 1 a week since that it all that I can afford right now. If more groupons are available, I probably wouldn't buy more unless it was a killer deal.
I don't have a particular schedule for my Groupon purchases, but if I see something convenient (that I would have bought anyway) or cool (that I wouldn't have bought except for the Groupon -- window purchases, basically,) I buy them.
This means that in the past month or so, I bought a Groupon for Baltimore Coffee & Tea, which means I got my $34.95 a pound Kona coffee for roughly $17, and flying lessons, which is something I've pondered before, but never pulled the trigger on.
Half off is a fine motivator.
I'd be happy to spend more money with Groupon if there were more interesting offers being presented, and upping the quantity of those offers is likely to increase the odds of that happening.