I've got one of several hot takes in zoo exhibit design as someone who studies it as a hobby and shakes my head whenever there is a lack of this particular element in certain exhibits, but here goes - moats are good, and the recent practice of phasing them out in favor of mesh fences and glass viewing windows (or cable fences in the case of large mammals *cough cough Atlanta* is aggravating personally. That said, I completely understand smaller zoos that don't utilize moats, as their intent is to maximize the amount of space given to their animals. My belief when it comes to exhibiting animals, is that there ideally would be different ways of viewing that would please the general public. Moats for completely unobstructed viewing, mesh/harp wire for getting closer to the animal (and actually using your five/six senses to fully comprehend what's coming your way), and glass for absolutely up-close viewing. As stated earlier, I completely understand the reason for moats not being utilized in smaller zoos like Akron, whose main goal is to maximize the amount of space that any given animal has, i.e. large predators and lesser apes. It can also be an issue of resources and animal husbandry where it's difficult to clean moats. And I also understand the necessity of prioritizing up-close viewing in terms of animals like snow leopards, jaguars and cougars, all of which are incredibly powerful jumpers that need fully meshed over habitats. That said, if a zoo is large enough and has the resources for implementing unobstructed viewing like moats and it chooses not to anyway, I see that as a missed opportunity of the highest order. (Looking at you, San Diego Zoo, making history with the U.S.'s first moated lion exhibit only for their modern-day habitat to be a dinky little netted over cage.)
TL;dr, moats good, small zoos don't use them for completely understandable reasons, but bigger zoos should use them especially if they have the space and budget.