they have no significant effect on minified and gziped size. in fact
they make things worse.
file | before | after removal
----------------------------------------
concat | 325415 | 325297
min | 62070 | 62161
min + gzip | 25187 | 25176
The bottom line is that we are getting 0.05% decrease in size after
gzip without all of the hassle of using underscores everywhere.