I think it's a good idea. Many hubber's already compose their hubs on another platform to start; which might have one, but an inbuilt one would be useful.
I had to think about this one for a few minutes before answering. My position is that this world of HP is for writers, and for writers to hone their writing skills. And, although this is a genteel site and no one would ever leave heavy criticisms on another's writing, the level of reads and comments that a Hub gets is a sure indicator to a writer of the quality and acceptance of their Hub, and that includes grammar.
Besides, if you add a grammar checker, HP would never be able to control the surge of new third-world (?) people, most of whom look to HP as a way to make easy money by plagarizing and using computer-generated converted text as their tools for Hubs. I mean, is there a brochure, written in English, left in a hotel anywhere in India, that hasn't been presented to us as a Hub? Again, HP is for writers, and very few get heady renumeration for what they present here on HP.So, in my opinion, let's all put our stuff out there, warts and all, for our fellow writers to see and hopefully enjoy.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.