Quote: "Surprising that both the mods are handled by hockeykid only"
I think it is only surprising if you are unaware of the history of these mods. He only recently acquired PBUM. Previously it was under the control of s4real and Plystire. PB itself represents the collective works of s4real, Plystire, Airslide, knxrb, URLforce and others who I have surely forgotten. Many of whom received a percentage of PB sales for their hard work.
You certainly don't have to choose, PB. However, it is (and will likely remain) the only option for those who wish to have asymmetric dual wielding. If you can eliminate the need for that and are not an FPI enthusiast, there is little reason not to stay with Fenix.
Trust me when I say that it's much better to be trapped in a dilemma than to have no options at all. As was the case when I and many others fist came to this community. The source code is available should you not find what is available to your satisfaction.
You are more than free to write your own mod in any way you see fit. You can rewrite FPSC to use a plugin system if you like. However, I'm sure you'll spend more in electricity before you even get your bearings straight. And in six months to a year or more when you complete something of use you will likely want to recover some of your invested cost (if it is for other than personal use); at which point you will encounter others with the same dilemma you have today.
As for why mods are not done through a plugin system; only Lee could answer that. My guess is that FPSC was never intended to have engine modification on the user-side. It's our good fortune that the FPSC source code is provided at all; giving those with moxie the option of pushing the possibilities of the platform to the heights we currently enjoy.