its less readable to me . isnt good python code meant to be easy to read

• easier to read than code with several lines (as long as the line is not too long/convoluted, ofc. And ofc, you need just a bit of practice to know about this kind of construct to read them easlily)
• easier to maintain (well, that shouldn't be needed for that kind of function)
• generally faster than deployed loops (well, doesn't really apply here, unless you're crazy enough to use a for loop when joining the chars ;) ), assuming the behavior of the code is the same
• ...well , that's cooler too. ;)

well, yes, I like the word "well"... x)