When writing code for both client and server, it's difficult to mentally "switch".
E.g. after writing some code in client, I'm starting placing curly braces in python's code :)
It would be nice to write both client and server in one language.
In my opinion, this argument have existential consequences: either it's not possible to emulate mind on turing machine or we don't have qualia and consciousness (it's just the illusion, that we have). And i don't like the latter.
Internet is already influencing governments to some extent. Rally in Moldova last year (which become a riot) was organized mostly with Twitter and Facebook.
It would be nice to write both client and server in one language.