The zoo is currently preparing for AZA accreditation, so many improvements are being made both in the public areas and behind the scenes. Unfortunately, there is a lot that goes on in the background that affects how quickly changes can be made and which ones are prioritized. Zoo New England (Franklin Park and Stone zoos) has a lengthy master plan that covers many years in the future. Unfortunately, with the current President/CEO retiring, many of the details have yet to be ironed out. Once his replacement is selected the executive team and board can begin working on that.
What sometimes gets lost when imagining improvements is the staffing and funding needed to complete those improvements. To revamp just one exhibit means that the animals have to be moved elsewhere or kept in a behind the scenes area (and not all animals have a dedicated off-exhibit area). Depending on the changes being made, nearby species may also need to be relocated to prevent stress from construction noises or to allow access to the exhibit being modified (trucks, plumbing/electrical lines, etc.). In addition to the material costs for the exhibit, contractors need to be hired to complete the modifications. There's so much more that goes into these types of things than it appears at first glance.
The giraffe barn is a prime example. It's something the zoo has wanted to do for many years, but the logistics are complex. There is nowhere else onsite where the animals can be moved during construction, and giraffes can be easily stressed by sudden major changes to their environment. The animals would need to be transferred to another zoo, and transporting a full-grown bull is monumental (Chad is ~ 2,800 lbs and over 17 feet tall). Construction would likely take longer than one season, so the zoo would be without a major species during the busy season. Revenue would be lost from no longer being able to do giraffe feeding experiences with guests, and if you're choosing which zoo to visit because that's an animal you want to see then you'll probably go to Southwick's or Roger Williams (more lost revenue).
Additionally, to host more activities for engaging visitors means more staff is needed, whether that's outside companies like for the lanterns or more zoo staff to host daytime activities or after-hours events. You can only spend each dollar once, so you need to be pragmatic about what you do. When it comes to these types of things, ramping up slowly is better; add a few new staff to cover a few new events/activities which will bring in more guests and that additional revenue can be used in the future to add even more staff/events.
I can confirm that several of the above suggestions are being looked into already and some even have plans in the works. But it takes time, money, and a lot of collaboration to make significant changes, so be patient, we're working on it!