I'm no dev myself, (not for the new sim at least. I used to make sceneries for FSX/P3D) but I like reading development updates from my favorite addon devs and in there they usually explain why they are no longer developing for X platform and why Z platform provides A, B, C, etc. Advantages over X.
And yes, it's true that at launch, MSFS was quite buggy, but Asobo has been hard at work fixing the big issues and bringing us free content updates as well. They are dedicated to making this new platform the best it can be. And sure, if your favorite plane is not in MSFS then keep using what you have, but you really shouldn't expect people to still talk about your 14 year old flight sim when a newer, better platform has arrived. One which provides both the addon developers and the end user a better experience for the most part (unless your favorite plane isn't in the sim, but hey, it's less than a year old) and if it doesn't, it's in continued development, so chances are that any issues you have with it will be fixed in a future update.
And personally I can't say I've had "bug-free" experiences with FSX and P3D. They were both, in fact, quite buggy, mostly because it's using more than 14 year old, 32-bit code on modern 64-bit computers and that makes the devs have to develop in 32-bit also, which in turn makes addons break more often. When i moved on to the new sim I was, quite frankly, relieved that I didn't have to deal with the many bugs I had on FSX/P3D.
About the systems depth, like I said, we have some pretty good addons already in the sim like the A32NX, the Working Title G1000, G3000, and Citation CJ4. These addons are payware quality and completely free and are much better than anything I ever had for FSX/P3D for the price. And on the payware side of things we have the Aerosoft CRJ and PMDG DC-6. All this less than a year since the sim's release, and there's still more to come from the big devs.
Maybe you don't think you're a badass, but I certainly see some people here who think it's a d*ck measuring contest on who has the oldest software.
Edit: I'd like to clarify that if you still use FS9, FSX, P3D, XPlane 10, whatever, I don't have a problem with that. What I have a problem with is people who say the new sim is bad or unrealistic and say that their outdated sim is better or more realistic in an aspect that it clearly isn't. If it works for you then that's great, use it, but accept that it's outdated and that because of that, people won't talk about it and addon companies won't support it.