Same here. There would definitely be small snails finding their way in there without it. If I ever spend the big bucks on an Abyzz I am definitely going to be looking into either buying an intake cage/strainer or maybe just modifying one that I already have.
Here's something for people who've had critters crawl into their skimmer intakes. When something blocks the intake, the amperage of the pump will typically go up significantly. If you run an Apex, you can set it to alert you to this condition. Several times I've been alerted and sure enough, had to remove snails and stars from skimmer intakes (before I repositioned my skimmers so animals couldn't get in so easily.)