A local internet registry at smallest only gets a /32.
This really depends on your region. My knowledge if from RIPE. The default allocation there is now a /29. But that is default. If you can justify more, you can have more.
I'm a fan of a /60 for homes. I guess you are right there is enough room to make a /48 work but that seems like needlessly throwing away a lot of bits.
Partially from a previous comment I've made:
Imagine that everyone on the planet is connected, and they each have 32 different ISPs (phones, home, work...) This is a gross overestimation.
7 billion people * 32 = 224 000 000 000 /48's required.
This easily fits within a single /10. That is 1/1024 of the total address space.
IPv4 currently has been around since around 1980 (Can't be bothered to get real dates). This means that it has so far had a life of around 40 years.
IPv6 is not going to last forever. It is very likely we will hit some limitation of the protocol, but its not likely to be with the address space. Lets use the IPv4 life length as a ball park figure for how long its going to last us.
Lets imagine in that time the population doubles, and the number of ISPs that everyone has doubles in that time.
We now have 14 billion people and 64 ISPs
14 billion people * 64 = 896 000 000 000 /48s required.
This comfortably fits within a /8 or 1/256 of the available address space.
Now we can do sparse addressing and leave big holes in the allocations "just in case" but we are still going to have a hell of a lot of address space left at this point.
Since we don't expect this protocol to last forever, why potentially stifle innovation by limiting addresses, when even using really outlandish figures for what may happen still leaves us with huge swaths of address space unused?
The current best practice allocation policies only affect the first /3, or 1/8 of the total available space. If we manage to burn through that quicker than expected, policies can be adjusted for the next /3.
I will begrudgingly accept for an ISP to hand me a /60 or a /56, but personally, I will be giving all my customers a /48. The space is so massive it seems rude not to.