The SDK was created simply for people like us (people who like to spend hundreds of hours hearing the communities thoughts and trying to make everything run smooth) hear hundreds of member whine, moan, complain, and mis-intrepret everything rather than reading the hundreds of lines of explanation in the SDK, the paragraphcs upon paragraphs of of description in the SDK topic, etc. We want everyone to hate it, because we are forcing you to use it.
In all seriousness, the SDK was created to make scripters lives more helpful. Before the SDK, I was making scripts about every 3 days. Unfortunately, once my name was noticed, I started spending more time fixing my scripts and trying to make them work for everyones individual game. I had no time to script, just support.
Then Near and Rataime put out the idea of the SDK. At first, I was confused, lost, and didn't think I would script for it. Once I got the idea behind it, I loved it and now, I won't script any other way. It makes everything much easier for me personally, because I don't have to hear "Make it work in my project."
Now, chances are it will work because it requires the SDK. I still hear "make it non-SDK", which isn't ever going to happen. I might point people in the right direction, but I would (and am) rather write a tutorial on converting SDK scripts to non-SDK and vice versa.
There is a lot of debate over SDK 1.5 and the new SDK 2.0+. This is really BS! The SDK 2.0+ is probably 200% if not more better than the 1.5. A, we fixed dozens of bugs that went undetected in the 1.5 version ; B) we divided up the SDK into multiple parts, so people don't have to use certain parts if their scripts don't require them ; C) we have included a error detection system that will now even record aliased and over-wrote methods to help find and detect scripts that conflict with eachother, which just rules ; D) We have added things like the Scene_Base class, which was developed to make Scene management in RMXP a hole lot easier. Many complained about the early 2.0 release, because we removed some methods, renamed some methods, etc., but the SDK 2.0+ patch fixes all of these concerns. There is no difference really. Most scripts (99%) of the SDK 1.5 scripts will still work if you have all 4 parts of the SDK 2.0+, its just now, more methods have been split, so scripts that over-wrote these methods have less a chance working, not that they have been over-writing these methods in the first place.
I think the SDK team and supporters have given more than enough time, patience, and reached out to help people who don't understand, don't support, etc., and get treated rather poorly in return.
Even if you don't code for the SDK, if you code properly, your script will probably work with the SDK, possibly only needing minor adjustment. No one is saying non-SDK < SDK or anything like that. All we are saying, is that for public copy-and-pasters, the SDK is the best thing for you in all truth. If you can script, you don't need the SDK and may only use things like the Scene_Base class.