I am not sure what are the advantages of 50MB block from technical point of view over say 20MB. But why people are so sceptical and bitcoin community is divided,
sure blockchain will be bigger but we have sufficient drives to cover it up. Isn't it our future and we will have to do this at some point? Why not do it now.
Here we go again. Looks like there will never be an end to the explaining. 20 MB is too much, especially for China where some large exchanges and miners are located.
Even though the general consensus seems to be that the blocks will get filled instantly (which they won't), there is potential for someone to try filling some of them for the wrong reasons.
China can't handle this right now. Besides 20 MB blocks are talk of the past, it should be 8 MB with the correct calculations. There is more consensus or 4 or 8 MB blocks as this would give the network more time before other solutions are found.
Increasing the block size is not the solution that we're seeking. Here is why:
It is believed that Visa is peaks at around 45, 000 tps (transactions per second). Bitcoin currently supports 7 tps (in theory; actually it is more around 2-3 but we're going to disregard this now) with a 1 megabyte block limit. If we use an average of 300 bytes per transaction and unlimited block size, an equivalent capacity to peak Visa transaction volume of 45,000 tps would be ~ 8 GB per block. This is every 10 minutes on average which would result over 400 petabytes per year.
Let me create a clearer picture:
400 Petabytes = 400 000 Terabytes = 400 000 000 Gigabytes per year.
You've read that correctly. That's 400 million Gigabytes per year if we only factor in what Visa is processing. Obviously this is not feasible (today) and this is why the block size increase is there only to buy time, nothing else.
It is possible that Moore's Law will continue forever, and that multi-gigabyte blocks may be a possibility of the future, however it is not a certainty. We can't rely on this scenario.
Note: Calculations have been done assuming a block is mined every 10 minutes totaling ~52,000 per year.
Update: Slight corrections.
Update 2: Thank you for informing me that 20 MB blocks are going to roll out.