What are the limitations of the Blu-ray format?

[Jezza]

I know this may come across as very controvesial on a Blu-ray forum, but I do think it is something that needs to be adressed for the future of the format and home entertainment.

Obviously by limitaions I mean 'what can't be done with Blu-ray that can be done with other formats' and are there any disadvantages to Blu-ray.

I'll give you one just to start off:
* It isn't designed to show SD - Which sounds stupid I know but think about it. Many television programmes prior to 2000 were shot in SD, which means that for them to be seen on BD properly they have to be in HD, yet not all things either can be or should be upscaled to HD. A good example could be sitcoms that may have been filmed on a pretty low resoultion SD camera, especially ones shot in the 1960s-1980s, and are they really worth upscaling even if you could?

So what do you think the limitations of Blu-ray are and do you agree with my example?