This isn't quite entirely true, for them address space is very tight and so they daren't just align everything and risk wasting too much address space, whereas on a 64-bit platform you can afford to be very generous with address space. This is akin to how it's fine to have randomised privacy addressing in IPv6, but that'd be a problem in IPv4. But this gain is hard to give a specific value to, whereas the simple fact is that 64-bit pointers are exactly twice as big as 32-bit pointers.

This can give you the incentive to build a different data structure, it's surprising how often "Just use a vector" is correct these days, Chandler Carruth has talked about that at length (in C++). If you have at least some idea how many Foozles you need, and Foozles aren't some crazy multi-page data structure, chances are you should put all the Foozles in a vector, and not carry around actual pointers to Foozles at all.