I'm not a designer, and have limited experience (Bootstrap, 960, Bourbon, etc) with (S){C,A}SS frameworks/libraries, so maybe I'm just being ignorant.
Can someone explain to me why there are so many grid frameworks? There appear to be quite a limited number of features, being responsive, dynamic grid sizes maybe? So what's the reason for so many designers 'rolling their own' 'handmade' 'little, tiny, light, nimble and small' grid frameworks?
I'm sure there is a reason for it, but from the perspective of an outsider (sort of), it looks like there is an excessive number of options.
Because why not? CSS is not like C code, speed or efficiency is really not that important here, reliability is. If it works you can use it or not. We're talking about shaving a few K at most off your file as the main benefit or maybe some minor compatibility improvements. These are important in some cases and unimportant in others. CSS solutions often are not one size fits all. Also it's important to know how these things work and I would posit it's probably easier to write one than to decipher someone else's code that may or may not have had the same goals as you.
Beginners are going to use whatever they always use, which is the thing that comes default or is the most popular. It's also a nice way to pad your Github for job apps.
Why are there so many MVC frameworks out there and so many redundant jQuery Plugins, doing all the same ( but in a different fashion )?
I think the answer is simple :
People learn and explore by doing such things.
I actually agree with you on this one. My only thought on it (from my perspective as a front-end developer) is with all these "do-everything" frameworks, I think I'm more interested in seeing a more minimalistic approach to these frameworks. I've used Bootstrap and found it often times to be incredibly bloated. I think people just want to able to do more with less.
Also, as developers, it's pretty natural if you can't find something (be it a tool, framework, plugin, etc) that you like to use, there's a feeling you can build something better yourself.
Of course there is no central planning authority, but there is a 'market' of sorts, that seems to have become saturated with many things that do the same thing.
For the less-abbreviation-wise NIH -> "Not Invented Here"
"is the philosophy of social, corporate, or institutional cultures that avoid using or buying already existing products, research, standards, or knowledge because of their external origins and costs." - http://en.wikipedia.org/wiki/Not_invented_here
Can someone explain to me why there are so many grid frameworks? There appear to be quite a limited number of features, being responsive, dynamic grid sizes maybe? So what's the reason for so many designers 'rolling their own' 'handmade' 'little, tiny, light, nimble and small' grid frameworks?
I'm sure there is a reason for it, but from the perspective of an outsider (sort of), it looks like there is an excessive number of options.