As for /48 IPv6 blocks being like /24 for IPv4. It really seems that /48 may be the most popular PI block and this may lead to overcrowding of DFZ. Probably, this is logical consequence of getting bigger address space. We needed more IP addresses and we get them. Anyway getting greater then /48 just because you do not want to pollute DFZ is not justified.
I agree with you except this last statement. If you have a need for more than a /48 and you can announce the aggregate and not the more specifics, it is perfectly valid to get more than a /48 and you should do so in a way that allows you to announce only the aggregate so as to avoid polluting the DFZ. DFZ pollution is not about prefix size, it is about the number of prefixes. In all cases, one should attempt to implement the minimum number of prefixes necessary to effect your desired (or needed) routing policy. Prefix size, OTOH, should relate to the number of end-sites served where each end-site gets a /48. Owen