Phonebloks looks cool, but…

I have no idea if this is a good idea, but it looks like a good idea and it sounds like a good idea. Perhaps someone with some degree of technical knowledge in this field could point out the pros, cons or (if required) the fact that it’s really obviously fatally flawed from the off?

The first main problem that I can see is that I’d obviously want the best camera, memory, processor and battery. Who wouldn’t?
And that’s surely not going to fit in my pocket. Which means compromise, which means lack of fulfillment, which means widespread disappointment and resentment, which means I’d hate my Phoneblok phone from the off and want an Xperia Z1, like I do now.