I can see the value of a lint (if there's a newline without a comma, warn), but concatenating strings by multiplication is the correct thing to do (since it's also used this way in mathematics of parsers). Using the plus operator to concatenate strings is just weird. Think of the usual algebraic properties these operators are supposed to have. "+" always is supposed to be commutative--so "a"+"b" = "b"+"a", if those m…
Furthermore, Python already uses * for strings to indicate repetition: ("foo" * 2 == "foofoo").
String concatenation really just needs its own separate operator. & is an obvious candidate, if only it wasn't so commonly appropriated for bitwise AND - which is a very poor use of a single-char operator as it's not something that you need often, especially in a language like Python.
On the other hand, D uses binary ~ for concatenation. That has a neat mnemonic: it's a "rope" that "ties strings together".