Yes, it's like on the CPC (6128), where the standard is also only 128K. Fortunately the VRAM is separated, so the MSX has additional 16K, which means, that in SymbOS there will be about 53KB free on an unexpanded system.
Btw, I like to work with BlueMSX, great emulator! 
Is it still beeing developed?
One important question: Which FDC is emulated in BlueMSX? I use the "MSX2" config. In the INI file I find "[FDC] Count=2" - what does it mean?
Great looking screenshots!, seems that you're progressing very fast!
I'm eager to see your first alpha release!.
I think the same than jltursan Unfortunately, I can't help you in tech and developping issues.
And BlueMSX, yes, it's still under development and their developers are Mars2000you and Dvik
Yours,
Yes, I already guessed that 
Regarding an alpha release, I hope this could be possible in one week, when the disc stuff is running. Today I want to finish most of all the other parts.
Prodatron: most (99%) MSX2 machines have 128kB VRAM, but you know that, right?
Also, most Japanese MSX2 and MSX2+ machines have only 64kB RAM. Most European MSX2 machines have 128kB RAM. TOday, many European MSX2 (and up) machines have 256kB RAM or more.
TurboR machines always have 256kB or more. As Takamichi said once: if your program needs more than 64k and it's for MSX2, you should label it 'turboR only' if you want to sell it in Japan