I don't consider rims cracking around the spoke holes after 4 years normal for a alloy rim. I've got alloy rims from the late seventies that don't have cracks. And none of my newer alloy rims do either. In fact I don't think I've ever had cracks around the spoke hole of any rim. Even the remaining Bontrager rim on my son's Marlin is in fine condition. And it is the rear which bears most of the weight and the differing tensions from drive side to non drive side spokes. And it's 8 yo.
If anything it's high end rims that will suffer the most from spoke tension not being correct. Low end stuff is heavier and more durable.