1) use `forward-sexp' instead of `forward-symbol'
2) implement a local version of `forward-symbol'
3) autoload `forward-symbol'
The problem with forward-sexp is that it won't do the same as
forward-symbol if it bumps into a parenthesis along the way.
Also if the user wants forward-sexp she can just use C-M-f.
So for all these reasons I think option 1 is not very good.
Note also that there's no reason why forward-symbol should be defined in
thingatpt.el, so it could also be moved to subr.el.
Stefan