When does the runner click for credits? When the runner needs money and doesn't have any better way to get it. Usually, but certainly not always, that means they're trying to get credits to install or play a card that will get them more credits. CPC Generator lets you capitalize on a runner who's economy is down to gain a maximum of 1 per turn.
Before you think it's a good deal though I present PAD Campaign which gives you 1 every turn regardless of what the runner does. Sure CPC Generator is 2 cheaper put it's also 2 easier to trash (not that it's going to be a high or even middle priority target).
If the runner's economy engine is running well CPC generator won't help since the runner won't click for credit. If the runner needs to click for credit chances are you're already winning as a corp and don't need the little trickle of money. And since it's likely the runner will get on their feet within a few turns or so you're unlikely to make more than 3 or so from a CPC Generator. Kinda underwhelming.
Maybe there are combos that CPC Generator works in? The obvious thing to look for is the keyword advertisement. There are currently three cards that mention that in their text: Ad Blitz, Rebranding Team, Spark Agency: Worldswide Reach. Rebranding Team just gives all assets advertisement, it doesn't do anything for assets that already have it. Ad Blitz is potentially interesting to mass install advertisements but at 1 per install and rez of CPC it's not a great deal. Spark Agency: Worldswide Reach is the most interesting of the three and the only one in which CPC Generator makes a little bit of sense as it'll cost the runner 1 when you rez it.
I guess you could try to use some kind of weird deck with Test Ground to repeatedly derez and rez a CPC Generator, but that's a load of money and clicks for very little impact.
If CPC Generator would trigger every time the runner clicks for credit maybe it would be a somewhat better card, but even then it's likely to be eclipsed by the standard Pad Campaign in terms of net profit.
This is another one for the "what were they thinking?" collection.