As it has been said previously, ALL engineering career fields are in critical demand within the AF. This is why the AF holds most of their ROTC scholarships for technical degrees, and chances are if you are given a technical degree scholarship by the AF, you WILL serve in a technical career field (so be careful accepting that scholarship just as a means to "pay for school" if you don't want to serve in that type of AF career).
What do AF engineers do? Well, many will start off doing the typical "engineering" type things you are thinking about: working on programs or in the acquisition of new systems. You may go to a technical school first before reporting to your first permanent duty station for a 3 year tour. But the AF isn't making you an officer to do that for long, or to do the "leg work" of engineering; we have plenty of civilian engineers and scientists with MANY years of experience to do that, or we contract this work out to some Defense Company. Instead, as an AF engineer, you will be asked to oversee the Defense Company's or civilian's efforts, verify they are fulfilling their contract. I see this A LOT in the F-35 program -- the AF has a TON of young Lts and Capts whose engineering job is to review the work being done by Lockheed Martin, Northrop Grumman, and a host of other defense contractors. Folks in the industry, with TONS of years of experience, having to demonstrate their work to young AF officers just like you.
And for you, this is a GOOD thing. You'll be put in that supervisor / program manager role at an age MUCH younger than your civilian counterparts (who more than likely won't ever get that chance until they are in their late 30s). You are making yourself a COMMODITY for when you do finally leave the service (and we all do leave eventually). If you decide to stay for 10 years in the AF? Well, at 32 you will be MUCH more experienced as a MANAGER and a LEADER in the engineering career field, and the benefit of that is you'll be making MUCH more than other engineers your age, with a lot more responsibility and potential to advance further.