It created a lot of troubles. Apparently, it was some arrangement pushed by the Regents decades ago, to hear DMACC tell it, but it's been an issue for transfers for a long, long time. Of course, every other school is running just like you describe, where a lab would be a 4th hour, but non-lab courses didn't have that.
One of the ways they held onto the 4 credit thing, per my interview a few years ago, was in attracting adjuncts, since they pay by the credit hour (for folks less familiar with all this). In terms of the class, it leads to including a lot that doesn't need to be there.
I sympathize with the folks complaining in one small aspect. I realize that they won't be teaching upper-level courses, and this is their only shot to get things in, but the stuff they kept bringing up is stuff I've never heard included, and sometimes hadn't even heard of. It's cool stuff, but not necessary for the survey class mission.
But yeah, they had 4 credit survey courses. Nobody mentioned the effect on pay, which was exactly my first thought. Otherwise, it just seemed to me like adapting to reality.