Who cares about these sizes though? I know I don't and nobody I know would either. 100Mb are downloaded in roughly 6 seconds with my connection at home.
But on a more serious note, I actually do care because I have around 4,500 packages installed on my system. If all of those were 100MB in size I'd have a problem.
With 50MB a piece that would be ~0.5TB. That is 50% of my system SSD.