I think that's a big differentiator in people's CLI preferences. When I see prompts that don't include $HOSTNAME, and people eschewing tabs for multiplexing in all cases I just assume they rarely manage remote machines.
also, using ^a^a to send commands to the nested tmux isn't so bad.. but to get to the third one down you need to use ^a^a^a^a as you need to send a ^a^a to the second one in..
for the fourth nest you need 8 ^a's, but again, it's a bit like code indentation, if you're 4 tmuxes deep, then there's a good chance you're doing it wrong
but still, it's nice to be able to do it if necessary